Pre-existing Thyroid Autoimmunity and Risk of Papillary Thyroid Cancer: A Nested Case-Control Study of US Active-Duty Personnel.

PURPOSE: Thyroid autoimmunity has been associated with differentiated thyroid cancer although multiple potential biases might have influenced the results of previous studies. METHODS: We conducted a case-control study nested within the cohort of US active-duty personnel 1996-2014 to assess the association between thyroid autoimmunity, defined by serology, and thyroid cancer diagnosis. The primary exposure was thyroid peroxidase (TPO) antibody status 7-10 years before the thyroid cancer index date. We also assessed whether diagnosis of thyroid autoimmunity mediated any associations identified and if thyroid cancer features differed by autoimmunity status. RESULTS: Among 451 incident cases of papillary thyroid cancer and matched controls (median age 36 years, 61.4% men), TPO antibody positivity (v negative) 7-10 years prediagnosis was associated with thyroid cancer (odds ratio [OR] 1.90 [95% CI, 1.33 to 2.70]). Exploratory analyses suggested an increasing risk of thyroid cancer with higher TPO antibody titer (TPO antibody 550-1,399 IU/mL: OR 2.95 [95% CI, 1.37 to 6.36]; and ≥ 1,400 IU/mL: OR 3.91 [95% CI, 1.66 to 9.24]). Positive TPO antibody status remained associated with thyroid cancer after those with diagnosed autoimmunity were excluded, and the association was not mediated by diagnosis of thyroid autoimmunity. Among the cases with diagnosed autoimmunity, 58% thyroid cancers were ≤ 10 mm diameter. CONCLUSION: Longstanding prior thyroid autoimmunity up to 10 years before thyroid cancer diagnosis was associated with papillary thyroid cancer risk. The results could not be fully explained by diagnosis of thyroid autoimmunity although when autoimmunity had been identified, thyroid cancers were diagnosed at a very early stage.

Differentiating between smokers and nonsmokers using serum cotinine.

Aim: Our goal is to evaluate implications of cotinine cut points in subgroups of smokers and nonsmokers. Materials & methods: Data were assessed from 13,357 adult participants and collected over a period of 6 years by the National Health and Nutrition Examination Survey (2009-2014). Receiver operating characteristic curve analysis was used to identify optimal cut points. Rao-Scott χ2 tests measured associations between group characteristics. Results: The optimal serum cotinine cut point adult cigarette smokers was 3.63 ng/ml (sensitivity of 96.7%; specificity of 93.0%). This cut point differed by gender as well as race/ethnicity. Conclusion: There are notable differences in subgroup cut points compared with previous research. Use of gender or race/ethnicity specific cut points is more appropriate when feasible and may help clinician recommendations.

Gender differences in the associations of body mass index, physical fitness and tobacco use with lower extremity musculoskeletal injuries among new US Army soldiers.

BACKGROUND: Musculoskeletal (MSK) injuries are a leading cause of morbidity among US Army soldiers, especially among women and the newly enlisted. While extremes of body mass index (BMI), low physical fitness and tobacco use have been identified as risk factors, no prior studies have determined the combined effects of these risk factors or tested for gender differences in the associations. METHODS: We conducted a retrospective cohort study utilising the Stanford Military Data Repository to study all enlisted soldier accessions to the US Army between January 2011 and January 2014, with follow-up through December 2014 (n=238 772). We used discrete-time logistic regression to test for associations between demographic, socioeconomic and health behaviour-related predictors and incident lower extremity injuries. We included interaction terms to test for gender differences. RESULTS: Among men, there were greater adjusted odds of injury among underweight (OR 1.27), overweight (OR 1.14) and obese soldiers (OR 1.54) (all p<0.001) relative to normal-weight soldiers. No statistically significant differences in the odds of injury on the basis of BMI were observed for female soldiers. Physical fitness was a significantly stronger predictor of injury for female as compared with male soldiers, while the association between tobacco use and injury was stronger for men (OR 1.47) than for women (OR 1.30) (p<0.001 for both). CONCLUSION: This is the largest known study to simultaneously assess important, modifiable musculoskeletal injury risk factors and to test for gender differences in these associations. These findings provide critical gender-related nuances for clinicians and leaders seeking to reduce the risk of these problems.

Epidemiologic Evidence and Possible Mechanisms for the Association Between Cigarette Smoking and Injuries. Part 2: Is the Relationship Between Smoking and Injuries Causal?

Part 1 of this series reviewed the epidemiologic evidence for the association between cigarette smoking and injuries and possible biological and psychosocial mechanisms to account for this relationship. In the present article, nine criteria are explored to determine if smoking is a direct cause of injuries (i.e., a causal relationship). There is substantial evidence that individuals who smoked in the past have a higher subsequent risk of injury. A recent meta-analysis found that smokers in the military were 1.31 times more likely to be injured than nonsmokers and Servicemembers with low, medium, and high levels of smoking had 1.27, 1.37, and 1.71 times, respectively, the risk of injury compared with nonsmokers. The association between smoking and injuries has been reported in at least 18 US military studies and in 14 civilian studies in seven countries. The biological plausibility of the association was discussed extensively in part 1 of this series. A possible alternative explanation with sufficient data was that smokers may be risk takers and it is the risk-taking behavior that increases injury risk (not smoking per se). Once an individual no longer smokes, a decrease in injury risk has been reported for at least bone health and wound healing. The effects of smoking do not appear to be specific to one type of injury, possibly because of the numerous compounds in tobacco smoke that could affect tissues and physiological processes, with evidence provided for bones, tendons, and healing processes. The association was consistent with other knowledge, with some evidence provided from other types of medical problems and trends in smoking and injury-related mortality. In summary, the association between smoking and injuries appears to meet many of the criteria for a causal relationship.

Epidemiological Evidence and Possible Mechanisms for the Association Between Cigarette Smoking and Injuries (Part 1).

Surveys indicated that 24% of military personnel are current cigarette smokers. Smoking is well known to increase the risk of cancers, cardiovascular and respiratory diseases, reproductive problems, and other medical maladies, but one of the little known effects of smoking is that on injuries. There is considerable evidence from a variety of sources that (1) smoking increases overall injury risk, (2) the greater the amount of smoking, the higher is the injury risk, and (3) smoking is an independent injury risk factor. Smoking not only affects the overall injury risk but also impairs healing processes following fractures (e.g., longer healing times, more nonunions, more complications), ligament injury (e.g., lower subjective function scores, greater joint laxity, lower subsequent physical activity, more infections), and wounding (e.g., delayed healing, more complications, less satisfying cosmetic results). Smoking may elicit effects on fractures through low bone mineral density (BMD), lower dietary intake of calcium and vitamin D, altered calcium metabolism, and effects on osteogenesis and sex hormones. Effects on wound healing may be mediated through altered neutrophils and monocytes functions resulting in reduced ability to fight infections and remove damaged tissue, reduced gene expression of cytokines important for tissue healing, and altered fibroblast function leading to lower density and amount of new tissue formation. Limited data suggest smoking cessation has favorable effects on various aspects of bone health over periods of 1 to 30 years. Favorable effects on neutrophil and monocyte functions may occur as early as 4 weeks, but fibroblast function and collagen metabolism (important for wound remodeling) appear to take considerably longer and may be dependent on the amount of prior smoking. Part 2 of this series will use this information to explore the possibility of a causal relationship between smoking and injuries.

Meta-analysis of Cigarette Smoking and Musculoskeletal Injuries in Military Training.

PURPOSE: Tobacco use is common among military personnel, as is musculoskeletal injury during training. In a review of the literature on musculoskeletal injuries, there was mixed evidence on the role of smoking as a risk factor. The purpose of this study is to review and analyze the literature on the impact of cigarette smoking on lower-extremity overuse injuries in military training. METHODS: We performed a literature search on articles published through October 2016. Search terms focused on lower-extremity overuse musculoskeletal injuries and cigarette smoking in military populations. We conducted a meta-analysis overall and by sex, including smoking intensity. RESULTS: We identified 129 potential studies and selected 18 based on quality. The overall rate ratio for smoking was 1.31, 1.31 for men, and 1.23 for women. Overall and for each sex, rate ratios were significantly greater than 1.0 for each intensity level of smoking. CONCLUSIONS: Smoking is a moderate risk factor for musculoskeletal injury and may account for a meaningful proportion of injuries among men and women due to the high prevalence of smoking and injury in this population. Although enlistees are not allowed to smoke during basic training, their risk of injury remains high, indicating that smokers may remain at increased risk for medium- to long-term duration.

Effect of pre-accession physical fitness on training injuries among US Army recruits.

OBJECTIVE: To evaluate the association of pre-accession physical fitness, as measured by a five-minute step test, with incidence of overuse injuries and outpatient healthcare utilization among male United States (US) Army recruits. PARTICIPANTS: US Army male trainees who met weight standards and took a pre-accession fitness test. METHODS: In this prospective cohort study, incidence and outpatient healthcare visits for overuse injuries during the first 90 days of military service were compared between recruits who failed the pre-accession step test with those who passed. RESULTS: The hazard rate ratio for injury among recruits who failed the fitness test compared to those who passed the test was 1.31 (95% C.I = 1.20-1.44). Among the subset of recruits with at least one medical encounter for an overuse injury, the utilization rate ratio for subjects who failed the fitness test versus those who passed was 1.15 (95% C.I = 1.09-1.22). Other factors associated with increased risk of injury or healthcare utilization include age, body mass index, and smoking history. CONCLUSIONS: Risk of injury and utilization were associated with fitness test results. These findings may have implications for military accession and training policy as well as for other physically demanding training programs such as police, fire fighters and athletes.

Step test performance and risk of stress fractures among female army trainees.

BACKGROUND: Stress fractures and other musculoskeletal injuries are major sources of morbidity among female military trainees. Several risk factors have been postulated, particularly pre-existing fitness, usually assessed with post-entry run time for ≥ 1.0 mile. PURPOSE: Physical fitness is not formally evaluated prior to Army entry. If a valid and simple test that identified women at increased risk of stress fracture were available and could be applied prior to entry, it would facilitate cost-benefit studies of deferral or interventions. These analyses were undertaken to determine if a 5-minute step test conducted before entry identified women at increased risk. METHODS: A prospective study was conducted of weight-qualified women entering the Army in 2005-2006, with analyses completed in 2011. At the pre-entry examination, information was collected on age, BMI, smoking, race, and activity level. Everyone took the step test. All outpatient medical encounters were captured, and stress fractures and other musculoskeletal injuries identified. Women with stress fractures and those with other musculoskeletal injuries were evaluated separately. RESULTS: 1568 women were included in the study; 109 developed stress fractures and 803 other musculoskeletal injury. Women who failed the step test had a 76% higher stress fracture incidence and a 35% higher incidence of other musculoskeletal injuries. There was effect modification between age and test failure for stress fracture. CONCLUSIONS: A step test that can be administered before military entry identifies women with increased incidence of stress fracture and other musculoskeletal injury. This test could be used pre-entry to defer or target high-risk recruits for tailored fitness training before or after military entrance.

Self-reported physical activity and preaccession fitness testing in U.S. Army applicants.

The Assessment of Recruit Motivation and Strength (ARMS) study evaluated a physical fitness screening test for Army applicants before basic training. This report examines applicants' self-reported physical activity as a predictor of objective fitness measured by ARMS. In 2006, the ARMS study administered a fitness test and physical activity survey to Army applicants during their medical evaluation, using multiple logistic regression for comparison. Among both men and women, "qualified" and "exceeds-body-fat" subjects who met American College of Sports Medicine adult physical activity guidelines were more likely to pass the fitness test. Overall, subjects who met physical activity recommendations, watched less television, and played on sports teams had a higher odds of passing the ARMS test after adjustment for age, race, and smoking status. This study demonstrates that self-reported physical activity was associated with physical fitness and may be used to identify those at risk of failing a preaccession fitness test.

Weight loss in diabetes management.

Type 2 diabetes and obesity are increasing dramatically in the United States and in many parts of the world. Both diseases have substantial public health consequences in terms of associated morbidity and mortality. In obese individuals with diabetes, weight loss can bring several physical and psychological benefits: decreased glycosylated hemoglobin and blood pressure, improved lipid levels, and elevated sense of well-being. A combination of diet, exercise, and behavioral therapy, which are considered components of lifestyle modification, is recommended as the first strategy. If an individual is unresponsive to these approaches or has comorbidities that are currently compromising his or her health, pharmacotherapy and/or surgery may be advised. Weight management counseling can prove challenging in diabetes care for the health provider but it is vital for the individual with diabetes in terms of preventing or delaying further morbidities.