Association between job control and time to pregnancy in a preconception cohort.

OBJECTIVE: To evaluate associations between low job control (operationalized as job independence and freedom to make decisions) and time to pregnancy. Low job control, a form of workplace stress, is associated with adverse health outcomes ranging from cardiovascular disease to premature mortality; few studies have specifically examined its association with reproductive outcomes. DESIGN: We used data from Pregnancy Study Online, an internet-based preconception cohort study of couples trying to conceive in the United States and Canada. We estimated fecundability ratios (FRs) and 95% confidence intervals (CIs) via proportional probability regression models, adjusting for sociodemographic and behavioral characteristics. SETTING: Not applicable (Web-based study). PATIENTS: Participants self-identified as female, were aged 21-45 years, and reported ≤6 cycles of pregnancy attempt time at enrollment (2018-2022). EXPOSURE: We assessed job control by matching participants' baseline self-reported occupation and industry with standardized occupation codes from the National Institute for Occupational Safety and Health's Industry and Occupation Computerized Coding System, then linking codes to O∗NET job exposure scores for job independence and freedom to make decisions. MAIN OUTCOME MEASURE: Our main outcome measure was fecundability. Participants completed self-administered questionnaires at baseline and every 8 weeks for up to 12 months or until reported pregnancy, whichever occurred first. RESULTS: Among 3,110 participants, lower job independence was associated with reduced fecundability. Compared with the fourth (highest) quartile, corresponding to the most job independence, FRs (95% CI) for first (lowest), second, and third quartiles were 0.92 (0.82-1.04), 0.84 (0.74-0.95), and 0.99 (0.88, 1.11), respectively. Lower freedom to make decisions was associated with slightly reduced fecundability (first vs. fourth quartile: FR = 0.92; 95% CI: 0.80-1.05). CONCLUSION: Lower job control, a work-related stressor, may adversely influence time to pregnancy. Because job control is a condition of work (i.e., not modifiable by individuals), these findings may strengthen arguments for improving working conditions as a means of improving worker health, including fertility.

Male personal heat exposures and fecundability: A preconception cohort study.

BACKGROUND: Several studies indicate adverse effects of selected heat exposures on semen quality, but few studies have directly evaluated fertility as an endpoint. OBJECTIVE: We evaluated prospectively the association between male heat exposures and fecundability, the per-cycle probability of conception. MATERIALS AND METHODS: We analyzed data from 3041 couples residing in the United States or Canada who enrolled in a prospective preconception cohort study (2013-2021). At enrollment, males reported on several heat-related exposures, such as use of saunas, hot baths, seat heaters, and tight-fitting underwear. Pregnancy status was updated on female follow-up questionnaires every 8 weeks until conception or a censoring event (initiation of fertility treatment, cessation of pregnancy attempts, withdrawal, loss to follow-up, or 12 cycles), whichever came first. We used proportional probabilities regression models to estimate fecundability ratios (FR) and 95% confidence intervals (CIs) for the association between heat exposures and fecundability, mutually adjusting for heat exposures and other potential confounders. RESULTS: We observed small inverse associations for hot bath/tub use (≥3 vs. 0 times/month: FR = 0.87, 95% CI: 0.70-1.07) and fever in the 3 months before baseline (FR = 0.94, 95% CI: 0.79-1.12; one cycle of follow-up: FR = 0.84, 95% CI: 0.64-1.11). Little association was found for sauna use, hours of laptop use on one's lap, seat heater use, time spent sitting, and use of tight-fitting underwear. Based on a cumulative heat metric, FRs for 1, 2, 3, and ≥4 versus 0 heat exposures were 0.99 (95% CI: 0.87-1.12), 1.03 (95% CI: 0.89-1.19), 0.94 (95% CI: 0.74-1.19), and 0.77 (95% CI: 0.50-1.17), respectively. Associations were stronger among men aged ≥30 years (≥4 vs. 0 heat exposures: FR = 0.60, 95% CI: 0.34-1.04). CONCLUSION: Male use of hot tubs/baths and fever showed weak inverse associations with fecundability. Cumulative exposure to multiple heat sources was associated with a moderate reduction in fecundability, particularly among males aged ≥30 years.

A Prospective Study of Male Depression, Psychotropic Medication Use, and Fecundability.

We examined the associations of male depression and psychotropic medication use with fecundability in a North American preconception cohort study (2013-2020). Men aged ≥21 years completed a baseline questionnaire with questions on history of diagnosed depression, the Major Depression Inventory (MDI), and psychotropic medication use. Pregnancy status was updated via bimonthly female follow-up questionnaires until pregnancy or 12 menstrual cycles, whichever occurred first. Analyses were restricted to 2,398 couples attempting conception for ≤6 menstrual cycles at entry. We fit proportional probabilities models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for age (male and female), education, (male and female), race/ethnicity, physical activity, alcohol intake, body mass index, smoking, and having previously impregnated a partner. Nearly 12% of participants reported a depression diagnosis; 90.6% had low depressive symptoms (MDI <20), 3.5% had mild symptoms (MDI: 20-24), 2.7% had moderate symptoms (MDI: 25-29), and 3.3% had severe symptoms (MDI: ≥30). A total of 8.8% of participants reported current use of psychotropic medications. History of depression was associated with slightly reduced fecundability, although this result was also reasonably compatible with chance (FR = 0.89; 95% CI: [0.76, 1.04]). FRs for mild, moderate, and severe compared with low depressive symptoms were 0.89 (95% CI: [0.66, 1.21]), 0.90 (95% CI: [0.62, 1.31]), and 0.88 (95% CI: [0.65, 1.20]), respectively. This indicates little evidence of a dose-response relationship for depressive symptoms with fecundability, although estimates were imprecise. Current psychotropic medication use mediated 44% of the association between depressive symptoms and fecundability.

The association between work hours, shift work, and job latitude with fecundability: A preconception cohort study.

The role of occupational stress on male fertility is understudied. We examined associations between male occupational stress and fecundability. We used data from Pregnancy Study Online (PRESTO), a North American preconception cohort study. At baseline (2013-2019), male participants aged ≥ 21 years completed a baseline questionnaire on employment status, hours worked per week, time of day worked (daytime, evening, nights, and changing or rotating shifts), and job title. We used the O*NET occupational database to rate independence by job title. Female partners were followed via bimonthly follow-up questionnaires for 12 months or until pregnancy. We restricted analyses to 1,818 couples attempting conception for ≤ 6 cycles at enrollment. We used proportional probabilities regression to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs). The FR comparing unemployed with employed men was0.84 (95% CI: 0.62-1.14). Among employed men, FRs and 95% CIs for evening shift work, night shift work, and rotating shift work were 0.89 (95% CI: 0.68-1.17), 0.94 (95% CI: 0.66-1.33), and 0.91 (95% CI: 0.75-1.11) relative to daytime shift work. The FR for any nondaytime shift work was 0.91 (95% CI: 0.78-1.07). Total work hours (long or short) and job independence scores were not appreciably associated with fecundability. In conclusion, working nondaytime shifts and being unemployed were associated with slightly decreased fecundability. However, the variability in these estimates was substantial and the results were reasonably consistent with chance. Little association was observed for other occupation measures. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

A North American prospective study of depression, psychotropic medication use, and semen quality.

OBJECTIVE: To evaluate the associations of a history of diagnosed depression, current depressive symptoms, and recent use of psychotropic medications with semen quality and to consider mediation of the association between depression and semen quality by medication use. DESIGN: Prospective cohort study. SETTING: United States. PATIENT(S): The patients were 329 men aged ≥21 years (566 semen samples) who participated in a semen-testing substudy of Pregnancy Study Online. Pregnancy Study Online is an ongoing, web-based preconception cohort study of couples attempting to conceive. At baseline, participants reported information about depression diagnosis, depressive symptoms using the Major Depression Inventory, medication use in the last 4 weeks, and selected covariates. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The men used an at-home semen-testing kit (Trak; Sandstone Diagnostics, Inc., Pleasanton, California) to measure semen volume, sperm concentration, and motile sperm concentration. We calculated percent motility, total sperm count in the ejaculate, and total motile sperm count. RESULT(S): Forty-nine men (15%) reported a history of depression diagnosis, and 41 (12%) reported recent use of psychotropic medications. A history of depression diagnosis was associated with a 4.3-fold increase in the risk of low semen volume (<1.5 mL) (95% CI 1.16, 16). A 5-unit increase in Major Depression Inventory score was associated with a 1.38-fold increase in the risk of low semen volume (95% CI 0.92, 2.1). The results for other semen parameters were inconsistent. Recent use of psychotropic medications was associated with worse semen quality, and this association was confounded by a history of depression diagnosis. The observed association between depression and semen volume showed little mediation by psychotropic medication use. CONCLUSION: A history of diagnosed depression and severe depressive symptoms at enrollment were associated with low semen volume.

Timing of stress fracture in soldiers during the first 6 career months: a retrospective cohort study.

CONTEXT: Stress fractures (SF) are injuries that can result from beginning new or higher volume physical training regimens. The pattern of clinical presentation of SF over time after individuals start a new or more demanding physical training regimen is not well defined in medical literature. OBJECTIVE: Report trends in the clinical presentation of stress fractures over the first six month of soldiers' time in the service. DESIGN: Retrospective Cohort study Setting: This study was conducted using medical encounter and personnel data from U.S. Army soldiers during the first 6 months of their career. PARTICIPANTS: U.S. Army soldiers beginning their careers from 2005-2014 (N=701,027). DATA COLLECTION AND ANALYSIS: Weekly SF numbers and incidence were calculated overall, as well as by sex, over the first 6 months of military service. RESULTS: SF diagnoses (N=14,155) increased steeply in weeks 3 and 4, with a peak in the overall incidence of SF diagnoses occurring during weeks 5-8. Although clinical incidence of stress fracture generally decreased beyond 8 weeks, incident lower extremity stress fractures continued to present for over 20 weeks. The hazard ratio (HR) for SF among women compared to men was 4.14 (95% CI = [4.01, 4.27]). CONCLUSIONS: Across the 6-month study period, women showed over 4 times greater hazard for stress fracture. The results also suggest that health care providers should be particularly vigilant for stress fractures within 3 weeks after the beginning of a new or higher intensity exercise regimen. The incidence of SF may continue to climb for several weeks. Even as stress fracture incidence declines, it should be noted that these injuries may also continue to appear clinically even several months after a change in activity or training.

Seasonal patterns in fecundability in North America and Denmark: a preconception cohort study.

STUDY QUESTION: To what extent does fecundability vary across seasons? SUMMARY ANSWER: After accounting for seasonal patterns in pregnancy planning, we observed higher fecundability in the fall and lower fecundability in the spring, particularly at lower latitudes. WHAT IS KNOWN ALREADY: In human populations, there are strong seasonal patterns of births that vary across geographic regions and time periods. However, previous studies of seasonality and fecundity are limited because they examine season of birth rather than season of conception and therefore neglect to account for seasonal variation in initiating attempts to conceive or pregnancy loss or differences in gestational length. STUDY DESIGN, SIZE, DURATION: We conducted a preconception cohort study of 14 331 women residing in North America (June 2013-May 2018: n = 5827) and Denmark (June 2007-May 2018: n = 8504). Participants were attempting to conceive without fertility treatment and had been attempting pregnancy for ≤6 menstrual cycles at enrolment. PARTICIPANTS/MATERIAL, SETTING, METHODS: We collected information on season of each pregnancy attempt using last menstrual period dates over the study period. Pregnancy was reported on female bi-monthly follow-up questionnaires. We fit log-binomial models with trigonometric regression to examine periodic variation in fecundability. We accounted for seasonal variation in initiation of pregnancy attempts by including indicator variables for menstrual cycle of attempt in the regression models. MAIN RESULTS AND THE ROLE OF CHANCE: Initiation of pregnancy attempts peaked in September, with stronger seasonality in North America than in Denmark (48 vs. 16% higher probability initiating attempts in September compared with March). After accounting for seasonal variation in initiation of pregnancy attempts, we observed modest seasonal variation in fecundability, with a peak in the late fall and early winter in both cohorts, but stronger peak/low ratios in North America (1.16; 95% confidence interval [CI]: 1.05, 1.28) than in Denmark (1.08; 95% CI: 1.00, 1.16). When we stratified the North American data by latitude, we observed the strongest seasonal variation in the southern USA (peak/low ratio of 1.45 [95% CI: 1.14, 1.84]), with peak fecundability in late November. LIMITATIONS, REASONS FOR CAUTION: We estimated menstrual cycle dates between follow-up questionnaires, which may have introduced exposure misclassification, particularly when women skipped follow-up questionnaires. We were unable to measure seasonally varying factors that may have influenced fecundability, including ambient temperature, vitamin D levels or infectious disease. WIDER IMPLICATIONS OF THE FINDINGS: An understanding of how fecundability varies across seasons could help identify factors that can impair reproductive function. Neglecting to account for seasonal variation in initiation of pregnancy attempts could bias estimates of seasonal patterns in fecundability. This is the first preconception cohort study to examine seasonal variation in fecundability after accounting for seasonality in initiation of pregnancy attempts. Fecundability was highest in the fall and lowest in the spring, with stronger effects in southern latitudes of North America, suggesting that seasonal exposures may affect fecundity. STUDY FUNDING/COMPETING INTEREST(S): This research was funded by the Eunice K. Shriver National Institute of Child Health and Human Development (R21-050264, R01-HD060680, R21-HD072326 and R01-HD086742) and the Danish Medical Research Council (271-07-0338). The authors declare no conflicts of interest.

Relationship of Strength and Conditioning Metrics to Success on the Army Ranger Physical Assessment Test.

Barringer, ND, McKinnon, CJ, O'Brien, NC, and Kardouni, JR. Relationship of strength and conditioning metrics to success on the army ranger physical assessment test. J Strength Cond Res 33(4): 958-964, 2019-The purpose of our study was to compare standard strength and conditioning assessments in the Ranger Athlete Warrior (RAW) assessments to a tactical assessment of the Ranger Physical Assessment Test (RPAT) to determine what influence, if any, that they may have on the RPAT outcome. We analyzed RAW and RPAT data on 1,141 soldiers attempting the Ranger Assessment and Selection Program I (RASP I) for entrance into the 75th Ranger Regiment as part of their routine program data collection from July 2014 to July 2017. We found better performance in the broad jump, pull-ups, and average 300-yard shuttle time was associated with improved odds of passing the RPAT. For every increasing 2.54 centimeters in broad jump, the odds of passing the RPAT increased by 4% (OR = 1.04, 95% CI [1.01-1.07]). Each additional pull-up was associated with 6% better odds (OR = 1.06, 95% CI [1.01-1.12]) of passing the RPAT, and every second faster in the 300-yard shuttle was associated with 9% better odds of passing the RPAT (OR = 1.09, 95% CI [1.03-1.14]). The results of this study indicate that lower-body power, pulling strength, and anaerobic conditioning seemed to have the greatest influence on RPAT success. Our current results provide guidance to Strength Coaches or TSAC-Fs preparing tactical athletes for this specific or similar tactical assessment as better performance was found for tactical athletes with greater lower-body power, pulling strength, and anaerobic endurance.

Nonsteroidal Anti-Inflammatory Drug Prescriptions Are Associated With Increased Stress Fracture Diagnosis in the US Army Population.

Stress fractures are common in military personnel and endurance athletes, and nonsteroidal anti-inflammatory drug (NSAID) use is widespread in these populations. NSAIDs inhibit prostaglandin synthesis, which blunts the anabolic response of bone to physical activity and could therefore increase risk of stress fracture. The objective of this study was to determine whether prescribed NSAIDs were associated with stress fracture diagnoses among US Army soldiers. We also aimed to establish whether acetaminophen, an analgesic alternative to NSAIDs, was associated with stress fracture risk. A nested case-control study was conducted using data from the Total Army Injury and Health Outcomes Database from 2002 to 2011 (n = 1,260,168). We identified soldiers with a diagnosis of stress fracture (n = 24,146) and selected 4 controls per case matched on length of military service (n = 96,584). We identified NSAID and acetaminophen prescriptions 180 to 30 days before injury (or match date). We also identified soldiers who participated in basic combat training (BCT), a 10-week period of heightened physical activity at the onset of Army service. Among these individuals, we identified 9088 cases and 36,878 matched controls. Conditional logistic regression was used to calculate incident rate ratios (RR) for stress fracture with adjustment for sex. NSAID prescription was associated with a 2.9-fold increase (RR = 2.9, 95% confidence interval [CI] 2.8-2.9) and acetaminophen prescription with a 2.1-fold increase (RR = 2.1, 95% CI 2.0-2.2) in stress fracture risk within the total Army population. The risk was more than 5-fold greater in soldiers prescribed NSAIDs (RR = 5.3, 95% CI 4.9-5.7) and more than 4-fold greater in soldiers prescribed acetaminophen (RR = 4.4, 95% CI 3.9-4.9) during BCT. Our results reveal an association between NSAID and acetaminophen prescriptions and stress fracture risk, particularly during periods of heightened physical activity. Prospective observational studies and randomized controlled trials are needed to support these findings before clinical recommendations can be made. © 2018 American Society for Bone and Mineral Research.

Risk for Lower Extremity Injury After Concussion: A Matched Cohort Study in Soldiers.

Background Rates of lower extremity musculoskeletal injury are reportedly higher in professional and collegiate athletes following concussions. However, there is a paucity of evidence on this relationship in individuals who are not high-level athletes. Objectives To examine the risk of acute lower extremity musculoskeletal injury in soldiers within 2 years of an incident concussion, compared to matched nonconcussed soldiers. Methods This was a matched-cohort study that used the medical encounter and personnel data of active-duty US Army soldiers from 2005 to 2011. Incident concussions were identified using International Classification of Diseases-Ninth Revision codes in medical encounter data of all soldiers from 2005 to 2009. One nonconcussed soldier in the US Army during the same month was matched by age, sex, rank, length of service, deployment status, and military career field to each concussed soldier. Hazard ratio (HR) and 95% confidence interval (CI) were calculated for the risk of lower extremity injury within 2 years of the incident concussion. Monthly HRs were compared to identify differences in injury rates between the groups, and an HR for the period of greatest difference was also calculated. Results A total of 23 044 individuals (11 522 concussed and 11 522 nonconcussed) were included in the study. Within 2 years of concussion, the hazard of lower extremity injury was 38% greater in concussed compared to nonconcussed soldiers (HR, 1.38; 95% CI: 1.30, 1.46), while the 15-month hazard was 45% greater (HR, 1.45; 95% CI: 1.36, 1.56). Conclusion The rate of lower extremity musculoskeletal injury among this population of physically active adults is higher following concussion, and the risk remains elevated for more than a year following injury. Level of Evidence Prognosis, level 2b. J Orthop Sports Phys Ther 2018;48(7):533-540. Epub 8 May 2018. doi:10.2519/jospt.2018.8053.

Risk Factors for Training-Related Injuries During U.S. Army Basic Combat Training.

Background: Injuries during basic combat training (BCT) impact military health and readiness in the U.S. Army. Identifying risk factors is crucial for injury prevention, but few Army-wide studies to identify risk factors for injury during BCT have been completed to date. This study examines associations between individual and training-related characteristics and injuries during Army BCT. Methods: Using administrative data from the Total Army Injury and Health Outcomes Database (TAIHOD), we identified individuals who apparently entered BCT for the first time between 1 January 2002 and 30 September 2007, based on review of administrative records. Injuries were identified and categorized based on coded medical encounter data. When combined with dates of medical services, we could count injuries per person, identify unique injuries, and identify the quantity and type of medical care delivered. Regression models produced odds ratios (ORs) and 95% confidence intervals (CIs) to identify risk factors for injury during BCT (yes/no), adjusted for potential confounders. Results: Of the 278,045 (83.4%) men and 55,302 (16.6%) women who were apparently first-time trainees, 39.5% (n = 109,760) of men and 60.9% (n = 33,699) of women were injured during training based on over 2 million recorded medical encounters entries. The large cohort yielded statistically significant, small magnitude associations between injury and all individual and training-related covariates for men, and all but medical accession waivers and weight for women. After adjustment, largest magnitude effects among men were due to age > 25 yr vs. 17-18 yr (OR = 1.83, 95% CI: 1.75, 1.91); having been married in the past vs. being single (OR = 1.36, 95% CI: 1.24, 1.49); rank E4-E7 vs. E1 (OR = 0.56, 95% CI: 0.53. 0.59); training at Ft. Jackson (OR = 0.66, 95% CI: 0.64, 0.69), Ft. Leonard Wood (OR = 0.67, 95% CI: 0.65, 0.70), or Ft. Knox (OR = 0.69, 95% CI: 066, 0.72) vs. Ft. Benning. Odds of injury were highest during 2005, 2006, and 2007. After adjustment for weight and body mass index, taller men had higher odds of BCT injury than average height men (OR = 1.08, 95% CI: 1.05, 1.11). Among women, short stature (OR = 1.11; 95% CI: 1.04, 1.19), training at Ft Leonard Wood (OR = 1.10; 95% CI: 1.04, 1.16) and evidence of injury prior to training based on accession waiver (OR = 1.12; 95% CI: 1.00, 1.26) increased injury risk. Conclusions: This Army-wide analysis reveals higher BCT-related injury rates for both men and women than prior studies and identifies risk factors for injuries during BCT. The large data set allows adjustment for many covariates, but because statistical analysis may yield significant findings for small differences, results must be interpreted based on minimally important differences determined by military and medical professionals. Results provide information that may be used to adapt training or medical screening and examination procedures for basic trainees.

Male sleep duration and fecundability in a North American preconception cohort study.

OBJECTIVE: To evaluate prospectively the association between male sleep duration and fecundability. DESIGN: Pregnancy Online Study (PRESTO), a Web-based prospective cohort study of North American couples enrolled during the preconception period (2013-2017). SETTING: Not applicable. PATIENT(S): Male participants were aged ≥21 years; female participants were aged 21-45 years. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): At enrollment, men reported their average nightly sleep duration in the previous month. Pregnancy status was updated on female follow-up questionnaires every 8 weeks for up to 12 months or until conception. Analyses were restricted to 1,176 couples who had been attempting to conceive for up to six cycles at enrollment. Proportional probabilities regression models were used to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders. RESULT(S): Relative to 8 hours per night of sleep, multivariable-adjusted FRs for <6, 6, 7, and ≥9 hours per night of sleep were 0.62 (95% CI 0.45-0.87), 1.06 (95% CI 0.87-1.30), 0.97 (95% CI 0.81-1.17), and 0.73 (95% CI 0.46-1.15), respectively. The association between short sleep duration (<6 hours per night) and fecundability was similar among men not working nights or rotating shifts (FR 0.60, 95% CI 0.41-0.88) and among men without a history of infertility (FR 0.62, 95% CI 0.44-0.87) and was stronger among fathers (FR 0.46, 95% CI 0.28-0.76). CONCLUSION(S): Short sleep duration in men was associated with reduced fecundability. Because male factor accounts for 50% of couple infertility, identifying modifiable determinants of infertility could provide alternatives to expensive fertility workups and treatments.

Dietary Fat Intake and Fecundability in 2 Preconception Cohort Studies.

The association between dietary fat and fertility is not well studied. We evaluated intakes of total fat, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, trans fatty acids (TFA), ω-3 fatty acids, and ω-6 fatty acids in relation to fecundability in Danish and North American preconception cohort studies. Women who were attempting to become pregnant completed a validated food frequency questionnaire at baseline. Pregnancy status was updated bimonthly for 12 months or until pregnancy. Fecundability ratios (FR) and 95% confidence intervals were estimated using multivariable proportional probabilities regression. Intakes of total fat and saturated, monounsaturated, polyunsaturated, and ω-6 fatty acids were not appreciably associated with fecundability. TFA intake was associated with reduced fecundability in North American women (for the fourth quartile vs. the first, FR = 0.86, 95% confidence interval (CI): 0.71, 1.04) but not Danish women (for the fourth quartile vs. the first, FR = 1.04, 95% CI: 0.86, 1.25), though intake among Danish women was low. In North America, ω-3 fatty acid intake was associated with higher fecundability, but there was no dose-response relationship (among persons who did not use fish oil supplements: for the fourth quartile vs. the first, FR = 1.40, 95% CI: 1.13, 1.73); no association was found in Danish women, among whom low intake was rare. In the present study, high TFA intake and low ω-3 fatty acid intake were associated with reduced fecundity.

Risk Factors for Mild Traumatic Brain Injury and Subsequent Post-Traumatic Stress Disorder and Mental Health Disorders among United States Army Soldiers.

The purpose of this study was to determine the association of mild traumatic brain injury (mTBI) with subsequent post-traumatic stress disorder (PTSD) and mental health disorders (MHD), and the intervening role of acute stress disorder (ASD). This matched case-control study utilized the Total Army Injury and Health Outcomes Database (TAIHOD) to analyze soldiers' (n = 1,261,297) medical encounter data between 2002 and 2011. International Classification of Diseases, Ninth Revision (ICD-9) codes were used to identify: mTBI (following Centers for Disease Control [CDC] surveillance definition for mTBI), MHD (ICD-9 codes for depression and anxiety, excluding PTSD), PTSD (ICD-9 309.81), and ASD (ICD-9 308.3). Incident cases of mTBI (n = 79,505), PTSD (n = 71,454), and MHD (n = 285,731) were identified. Overall incidence rates per 1000 soldier years were: mTBI = 17.23, PTSD = 15.37, and MHD = 67.99. mTBI was associated with increased risk for PTSD (risk ratio [RR] 5.09, 95% confidence interval [CI] 4.82-5.37) and MHD (RR 2.94, 95% CI 2.84-3.04). A sub-analysis of the mTBI-only soldiers found that a diagnosis ASD, compared with a diagnosis of no ASD, was associated with greater risk for subsequent PTSD (RR 2.13, 95% CI 1.96-2.32) and MHD (RR 1.90, 95% CI 1.72-2.09) following mTBI. Results indicate that soldiers with previous mTBI have a higher risk for PTSD and MHD, and that ASD may also mediate PTSD and MHD risk subsequent to mTBI. These data may help guide important surveillance and clinical rehabilitation considerations for high-risk populations.

Risk Factors for Rhabdomyolysis in the U.S. Army.

The standardized mortality rate of rhabdomyolysis (RM) in Active Duty U.S. Army Soldiers is considerably higher than in the civilian population. RM occurs when large amounts of intracellular contents from damaged skeletal muscle escape into circulation, leading to serious sequelae (e.g., acute renal failure, hyperkalemia, compartment syndrome). Extended physical exertion, especially in hot environments, and trauma can precipitate RM. The aim of this study was to identify RM risk factors among U.S. Active Duty Army (ADA) Soldiers. METHODS: This nested case-control study used data from the Total Army Injury and Health Outcomes Database (years 2004-2006) to examine RM among ADA male Soldiers. Demographic and occupational variables were identified as potential risk factors. Each RM case was age and date-matched to 4 controls. Adjusted odds ratios (OR) were computed using conditional logistic regression analyses. RESULTS: From years 2004 to 2006, 1,086 Soldiers (0.19%) met the study criteria for clinically diagnosed RM. Three variables were found to increase the odds of acquiring RM: (1) prior heat stroke, OR 4.95 (95% confidence interval [CI] 1.1-21.7); (2) self-reported Black race, OR 2.56 (95% CI 2.2-3.0); and (3) length of service (0-90 days), OR 2.05 (95% CI 1.6-2.7). CONCLUSION: There is a substantially greater likelihood for male U.S. Army Soldiers to develop RM who: (1) have had a prior heat injury, (2) self-report in the Black racial category, and (3) who are within the initial 90 days of service. Greater awareness of the risk factors associated with RM may improve force health protection and readiness through targeted mitigation strategies.

Risk of Stress Fracture Varies by Race/Ethnic Origin in a Cohort Study of 1.3 Million US Army Soldiers.

Stress fractures (SF) are common and costly injuries in military personnel. Risk for SF has been shown to vary with race/ethnicity. Previous studies report increased SF risk in white and Hispanic Soldiers compared with black Soldiers. However, these studies did not account for the large ethnic diversity in the US military. We aimed to identify differences in SF risk among racial/ethnic groups within the US Army. A retrospective cohort study was conducted using data from the Total Army Injury and Health Outcomes Database from 2001 until 2011. SF diagnoses were identified from ICD-9 codes. We used Cox-proportional hazard models to calculate time to SF by racial/ethnic group after adjusting for age, education, and body mass index. We performed a sex-stratified analysis to determine whether the ethnic variation in SF risk depends on sex. We identified 21,549 SF cases in 1,299,332 Soldiers (more than 5,228,525 person-years of risk), revealing an overall incidence rate of 4.12 per 1000 person-years (7.47 and 2.05 per 1000 person-years in women and men, respectively). Using non-Hispanic blacks as the referent group, non-Hispanic white women had the highest risk of SF, with a 92% higher risk of SF than non-Hispanic black women (1.92 [1.81-2.03]), followed by American Indian/Native Alaskan women (1.72 [1.44-1.79]), Hispanic women (1.65 [1.53-1.79]), and Asian women (1.32 [1.16-1.49]). Similarly, non-Hispanic white men had the highest risk of SF, with a 59% higher risk of SF than non-Hispanic black men (1.59 [1.50-1.68]), followed by Hispanic men (1.19 [1.10-1.29]). When examining the total US Army population, we found substantial differences in the risk of stress fracture among racial/ethnic groups, with non-Hispanic white Soldiers at greatest risk and Hispanic, American Indian/Native Alaskan, and Asian Soldiers at an intermediate risk. Additional studies are needed to determine the factors underlying these race- and ethnic-related differences in stress fracture risk. © 2017 American Society for Bone and Mineral Research.

Body Mass Index at Accession and Incident Cardiometabolic Risk Factors in US Army Soldiers, 2001-2011.

Individuals entering US Army service are generally young and healthy, but many are overweight, which may impact cardiometabolic risk despite physical activity and fitness requirements. This analysis examines the association between Soldiers' BMI at accession and incident cardiometabolic risk factors (CRF) using longitudinal data from 731,014 Soldiers (17.0% female; age: 21.6 [3.9] years; BMI: 24.7 [3.8] kg/m2) who were assessed at Army accession, 2001-2011. CRF were defined as incident diagnoses through 2011, by ICD-9 code, of metabolic syndrome, glucose/insulin disorder, hypertension, dyslipidemia, or overweight/obesity (in those not initially overweight/obese). Multivariable-adjusted proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) between BMI categories at accession and CRF. Initially underweight (BMI<18.5 kg/m2) were 2.4% of Soldiers, 53.5% were normal weight (18.5-<25), 34.2% were overweight (25-<30), and 10.0% were obese (≥30). Mean age range at CRF diagnosis was 24-29 years old, with generally low CRF incidence: 228 with metabolic syndrome, 3,880 with a glucose/insulin disorder, 26,373 with hypertension, and 13,404 with dyslipidemia. Of the Soldiers who were not overweight or obese at accession, 5,361 were eventually diagnosed as overweight or obese. Relative to Soldiers who were normal weight at accession, those who were overweight or obese, respectively, had significantly higher risk of developing each CRF after multivariable adjustment (HR [95% CI]: metabolic syndrome: 4.13 [2.87-5.94], 13.36 [9.00-19.83]; glucose/insulin disorder: 1.39 [1.30-1.50], 2.76 [2.52-3.04]; hypertension: 1.85 [1.80-1.90], 3.31 [3.20-3.42]; dyslipidemia: 1.81 [1.75-1.89], 3.19 [3.04-3.35]). Risk of hypertension, dyslipidemia, and overweight/obesity in initially underweight Soldiers was 40%, 31%, and 79% lower, respectively, versus normal-weight Soldiers. BMI in early adulthood has important implications for cardiometabolic health, even within young, physically active populations.

Menstrual cycle characteristics and fecundability in a North American preconception cohort.

PURPOSE: The aim of this study was to evaluate the association between menstrual cycle characteristics in early life and adulthood and fecundability. METHODS: Pregnancy Study Online (PRESTO) is an Internet-based preconception cohort study of pregnancy planners from the United States and Canada. During the preconception period, we enrolled 2189 female pregnancy planners aged 21-45 years who had been attempting conception for ≤6 cycles. Women self-reported menstrual cycle characteristics via an online baseline questionnaire, and pregnancy status was ascertained through bimonthly follow-up questionnaires. Proportional probabilities models were used to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders. RESULTS: Compared with usual menstrual cycle lengths of 27-29 days, cycle lengths of <25 (FR = 0.81, 95% CI: 0.54-1.22) and 25-26 days (FR = 0.92, 95% CI: 0.75-1.14) were associated with reduced fecundability. Compared with women who reached menarche at the age of 12-13 years, those who reached menarche at <12 years had reduced fecundability (FR = 0.87, 95% CI: 0.76-0.99). Women whose cycles never regularized after menarche (FR = 0.93, 95% CI: 0.81-1.06) had slightly reduced fecundability compared with women whose cycles regularized within 2 years of menarche. Bleed length and heaviness of bleeding were not appreciably associated with fecundability. CONCLUSIONS: Menstrual cycle characteristics, specifically cycle length and age at menarche, may act as markers of fertility potential among pregnancy planners.

Incidence of Shoulder Dislocations and the Rate of Recurrent Instability in Soldiers.

PURPOSE: Shoulder dislocations present a potentially debilitating injury for soldiers and other groups of physically active adults. The purpose of this study was to determine the 10-yr incidence rate of shoulder dislocations in soldiers, the percentage with recurrent instability, and risk factors for these injuries. METHODS: This retrospective cohort study used medical encounter data from U.S. Army soldiers to calculate the 10-yr incidence rate for shoulder dislocations and the percentage of chronic or recurrent injuries >3 months and ≤2 yr after the initial diagnosis. A Cox proportional hazards model was constructed using demographic variables (age, race, education level, marital status, and sex) to determine incidence rate ratios for risk factors related to shoulder dislocation. Logistic regression was used to calculate odds ratio for risk factors for recurrent injury, including concurrent diagnoses (brachial plexus or peripheral nerve injuries and fractures of the scapula or proximal humerus). RESULTS: There were 15,426 incident shoulder dislocations, with a 10-yr incidence rate of 3.13 per 1000 person-year. Soldiers ≤40 yr old showed greater risk for injury compared with those older than 40 yr. The incidence rate ratio for males compared with females was 1.64, 95% confidence interval = 1.55-1.74. Recurrent injury occurred in 28.7% of cases. Concurrent axillary nerve injury (odds ratio = 3.64, 95% confidence interval = 1.56-8.46) and age ≤35 yr were associated with greater risk of recurrence. CONCLUSION: Within the active duty U.S. Army, men and younger individuals showed greater risk for shoulder dislocations. Over one-quarter of incident cases became recurrent. Axillary nerve injuries and younger age increased the odds of recurrent injury.

Body mass index, physical activity and fecundability in a North American preconception cohort study.

OBJECTIVE: To evaluate the association between adiposity, physical activity (PA), and fecundability. DESIGN: Prospective cohort study. SETTING: Not applicable. PATIENT(S): A total of 2,062 female pregnancy planners from the United States and Canada who were enrolled during the preconception period. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Self-reported pregnancy. Fecundability ratios (FRs) and 95% confidence intervals (CIs) were estimated using proportional probabilities models that adjusted for potential confounders. RESULT(S): Relative to body mass index (BMI) 18.5-24 kg/m(2), FRs for BMI <18.5, 25-29, 30-34, 35-39, 40-44, and ≥45 kg/m(2) were 1.05 (95% CI 0.76-1.46), 1.01 (95% CI 0.89-1.15), 0.98 (95% CI 0.82-1.18), 0.78 (95% CI 0.60-1.02), 0.61 (95% CI 0.42-0.88), and 0.42 (95% CI 0.23-0.76), respectively. Reduced fecundability was observed among women with the largest waist-to-hip ratios (≥0.85 vs. <0.75; FR = 0.87, 95% CI 0.74-1.01) and waist circumferences (≥36 vs. <26 inches [≥90 vs. <66 cm]; FR = 0.80, 95% CI 0.59-1.01). Tendency to gain weight in the chest/shoulders (FR = 0.63, 95% CI 0.36-1.08) and waist/stomach (FR = 0.90, 95% CI 0.79-1.02), relative to hips/thighs, was associated with lower fecundability. Moderate PA was associated with increased fecundability (≥5 vs. <1 h/wk; FR = 1.26, 95% CI 0.96-1.65), but there was no dose-response relation. Among overweight/obese women (BMI ≥25 kg/m(2)), fecundability was 27% higher for vigorous PA of ≥5 versus <1 h/wk (95% CI 1.02-1.57). CONCLUSION(S): Various measures of overall and central adiposity were associated with decreased fertility among pregnancy planners. Vigorous PA was associated with improved fertility among overweight and obese women only; moderate PA was associated with improved fertility among all women.