Venous Thromboembolism (VTE) Incidence and VTE-Associated Survival among Olmsted County Residents of Local Nursing Homes.

Nursing home (NH) residency is an independent risk factor for venous thromboembolism (VTE), but the VTE burden within the NH population is uncertain. This study estimates VTE incidence and VTE-associated mortality among NH residents. We identified all NH residents in any NH in Olmsted County, Minnesota, United States, 1 October 1998 to 31 December 2005 and all first lifetime VTE among county residents to estimate VTE incidence while resident of local NHs (NHVTE), using Centers for Medicare and Medicaid Services Minimum Data Set and Rochester Epidemiology Project resources. We tested associations between NHVTE and age, sex and time since each NH admission using Poisson modelling. Additionally, we tested incident NHVTE as a potential predictor of survival using Cox proportional hazards, adjusting for age, sex and NH residency. Between 1 October 1998 and 31 December 2005, 3,465 Olmsted County residents with ≥1 admission to a local NH, contributed 4,762 NH stays. Of the 3,465 NH residents, 111 experienced incident NHVTE (2.3% of all eligible stays), for an overall rate of 3,653/100,000 NH person-years (NH-PY). VTE incidence was inversely associated with time since each NH admission, and was highest in the first 7 days after each NH admission (18,764/100,000 NH-PY). The adjusted hazard of death for incident NHVTE was 1.90 (95% confidence interval [CI]: 1.38-2.62). In conclusion, VTE incidence among NH residents was nearly 30-fold higher than published incidence rates for the general Olmsted County population. VTE incidence was highest within 7 days after NH admission, and NHVTE was associated with significantly reduced survival. These data can inform future research and construction of clinical trials regarding short-term prophylaxis.

Nursing Home Use Across The Spectrum of Cognitive Decline: Merging Mayo Clinic Study of Aging With CMS MDS Assessments.

BACKGROUND/OBJECTIVES: Objective, complete estimates of nursing home (NH) use across the spectrum of cognitive decline are needed to help predict future care needs and inform economic models constructed to assess interventions to reduce care needs. DESIGN: Retrospective longitudinal study. SETTING: Olmsted County, MN. PARTICIPANTS: Mayo Clinic Study of Aging participants assessed as cognitively normal (CN), mild cognitive impairment (MCI), previously unrecognized dementia, or prevalent dementia (age = 70-89 years; N = 3,545). MEASUREMENTS: Participants were followed in Centers for Medicare and Medicaid Services (CMS) Minimum Data Set (MDS) NH records and in Rochester Epidemiology Project provider-linked medical records for 1-year after assessment of cognition for days of observation, NH use (yes/no), NH days, NH days/days of observation, and mortality. RESULTS: In the year after cognition was assessed, for persons categorized as CN, MCI, previously unrecognized dementia, and prevalent dementia respectively, the percentages who died were 1.0%, 2.6%, 4.2%, 21%; the percentages with any NH use were 3.8%, 8.7%, 19%, 40%; for persons with any NH use, median NH days were 27, 38, 120, 305, and median percentages of NH days/days of observation were 7.8%, 12%, 33%, 100%. The year after assessment, among persons with prevalent dementia and any NH use, >50% were a NH resident all days of observation. Pairwise comparisons revealed that each increase in cognitive impairment category exhibited significantly higher proportions with any NH use. One-year mortality was especially high for persons with prevalent dementia and any NH use (30% vs 13% for those with no NH use); 58% of all deaths among persons with prevalent dementia occurred while a NH resident. CONCLUSIONS: Findings suggest reductions in NH use could result from quality alternatives to NH admission, both among persons with MCI and persons with dementia, together with suitable options for end-of-life care among persons with prevalent dementia.

Skilled Nursing Facility Use and Hospitalizations in Heart Failure: A Community Linkage Study.

OBJECTIVES: To examine the effect of skilled nursing facility (SNF) use on hospitalizations in patients with heart failure (HF) and to examine predictors of hospitalization in patients with HF admitted to a SNF. PATIENTS AND METHODS: Olmsted County, Minnesota, residents with first-ever HF from January 1, 2000, through December 31, 2010, were identified, and clinical data were linked to SNF utilization data from the Centers for Medicare and Medicaid Services. Andersen-Gill models were used to determine the association between SNF use and hospitalizations and to determine predictors of hospitalization. RESULTS: Of 1498 patients with incident HF (mean ± SD age, 75±14 years; 45% male), 605 (40.4%) were admitted to a SNF after HF diagnosis (median follow-up, 3.6 years; range, 0-13.0 years). Of those with a SNF admission, 225 (37%) had 2 or more admissions. After adjustment for age, sex, ejection fraction, and comorbidities, SNF use was associated with a 50% increased risk of hospitalization compared with no SNF use (adjusted hazard ratio, 1.52; 95% CI, 1.31-1.76). In SNF users, arrhythmia, asthma, chronic kidney disease, and the number of activities of daily living requiring assistance were independently associated with an increased risk of hospitalization. CONCLUSION: Approximately 40% of patients with HF were admitted to a SNF at some point after diagnosis. Compared with SNF nonusers, SNF users were more likely to be hospitalized. Characteristics associated with hospitalization in SNF users were mostly noncardiovascular, including reduced ability to perform activities of daily living. These findings underscore the effect of physical functioning on hospitalizations in patients with HF in SNFs and the importance of strategies to improve physical functioning.

Risk factors for venous thromboembolism after acute trauma: A population-based case-cohort study.

BACKGROUND: Predictors of venous thromboembolism (VTE) after trauma are uncertain. OBJECTIVE: To identify independent predictors of VTE after acute trauma. METHODS: Using Rochester Epidemiology Project (REP) resources, we identified all Olmsted County, MN residents with objectively-diagnosed incident VTE within 92days after hospitalization for acute trauma over the 18-year period, 1988-2005. We also identified all Olmsted County residents hospitalized for acute trauma over this time period and chose one to two residents frequency-matched to VTE cases on sex, event year group and ICD-9-CM trauma code predictive of surgery. In a case-cohort study, demographic, baseline and time-dependent characteristics were tested as predictors of VTE after trauma using Cox proportional hazards modeling. RESULTS: Among 200 incident VTE cases, the median (interquartile range) time from trauma to VTE was 18 (6, 41) days. Of these, 62% cases developed VTE after hospital discharge. In a multiple variable model including 370 cohort members, patient age at injury, male sex, increasing injury severity as reflected by the Trauma Mortality Prediction Model (TMPM) Mortality Score, immobility prior to trauma, soft tissue leg injury, and prior superficial vein thrombosis were independent predictors of VTE (C-statistic=0.78). CONCLUSIONS: We have identified clinical characteristics which can identify patients at increased risk for VTE after acute trauma, independent of surgery. Almost two thirds of all incident VTE events occurred after initial hospital discharge (18day median time from trauma to VTE) which questions current practice of not extending VTE prophylaxis beyond hospital discharge.

Direct Medical Costs Attributable to Cancer-Associated Venous Thromboembolism: A Population-Based Longitudinal Study.

PURPOSE: The purpose of this study is to estimate medical costs attributable to venous thromboembolism among patients with active cancer. METHODS: In a population-based cohort study, we used Rochester Epidemiology Project (REP) resources to identify all Olmsted County, Minn. residents with incident venous thromboembolism and active cancer over the 18-year period, 1988-2005 (n = 374). One Olmsted County resident with active cancer without venous thromboembolism was matched to each case on age, sex, cancer diagnosis date, and duration of prior medical history. Subjects were followed forward in REP provider-linked billing data for standardized, inflation-adjusted direct medical costs from 1 year prior to index (venous thromboembolism event date or control-matched date) to the earliest of death, emigration from Olmsted County, or December 31, 2011, with censoring on the shortest follow-up to ensure a similar follow-up duration for each case-control pair. We used generalized linear modeling to predict costs for cases and controls and bootstrapping methods to assess uncertainty and significance of mean adjusted cost differences. Outpatient drug costs were not included in our estimates. RESULTS: Adjusted mean predicted costs were 1.9-fold higher for cases ($49,351) than for controls ($26,529) (P < .001) from index to up to 5 years post index. Cost differences between cases and controls were greatest within the first 3 months (mean difference = $13,504) and remained significantly higher from 3 months to 5 years post index (mean difference = $12,939). CONCLUSIONS: Venous thromboembolism-attributable costs among patients with active cancer contribute a substantial economic burden and are highest from index to 3 months, but may persist for up to 5 years.

Childhood Attention-Deficit/Hyperactivity Disorder, Sex, and Obesity: A Longitudinal Population-Based Study.

OBJECTIVE: To assess obesity rates during childhood and young adulthood in patients with attention-deficit/hyperactivity disorder (ADHD) and age- and sex-matched controls derived from a population-based birth cohort because cross-sectional studies suggest an association between ADHD and obesity. PATIENTS AND METHODS: Study subjects included patients with childhood ADHD (n=336) and age- and sex-matched non-ADHD controls (n=665) from a 1976 to 1982 birth cohort (N=5718). Height, weight, and stimulant treatment measurements were abstracted retrospectively from medical records documenting care provided from January 1, 1976, through August 31, 2010. The association between ADHD and obesity in patients with ADHD relative to controls was estimated using Cox models. RESULTS: Patients with attention-deficit/hyperactivity disorder were 1.23 (95% CI, 1.00-1.50; P<.05) times more likely to be obese during the follow-up period than were non-ADHD controls. This association was not statistically significant in either sex (female participants: hazard ratio [HR], 1.49; 95% CI, 0.98-2.27; P=.06; male participants HR, 1.17, 95% CI, 0.92-1.48; P=.20). Patients with ADHD who were not obese as of the date ADHD research diagnostic criteria were met were 1.56 (95% CI, 1.14-2.13; P<.01) times more likely to be obese during the subsequent follow-up than were controls. This association was statistically significant in female study subjects (HR, 2.02; 95% CI, 1.13-3.60; P=.02), but not in male participants (HR, 1.41; 95% CI, 0.97-2.05; P=.07). A higher proportion of patients with ADHD were obese after the age of 20 years compared with non-ADHD controls (34.4% vs 25.1%; P=.01); this difference was observed only in female patients (41.6% vs 19.2%). There were no differences in obesity rates between stimulant-treated and nontreated patients with ADHD. CONCLUSION: Childhood ADHD is associated with obesity during childhood and young adulthood in females. Treatment with stimulant medications is not associated with the development of obesity up to young adulthood.

Trends in Coronary Atherosclerosis: A Tale of Two Population Subgroups.

BACKGROUND: We previously investigated trends in subclinical coronary artery disease and associated risk factors among autopsied non-elderly adults who died from nonnatural causes. Although grade of atherosclerosis declined from 1981 through 2009, the trend was nonlinear, ending in 1995, concurrent with increasing obesity/diabetes in this population. The previous study used linear regression and examined trends for all 4 major epicardial coronary arteries combined. The present investigation of coronary artery disease trends for the period 1995 through 2012 was prompted by a desire for more detailed examination of more recent coronary artery disease trends in light of reports that the epidemics of obesity and diabetes have slowed and are perhaps ending. METHODS: This population-based series of cross-sectional investigations identified all Olmsted County, Minnesota residents aged 16-64 years who died 1995 through 2012 (N = 2931). For decedents with nonnatural manner of death, pathology reports were reviewed for grade of atherosclerosis assigned each major epicardial coronary artery. Using logistic regression, we estimated calendar-year trends in grade (unadjusted and age- and sex-adjusted) for each artery, initially as an ordinal measure (range, 0-4); then, based on evidence of nonproportional odds, as a dichotomous variable (any atherosclerosis, yes/no) and as an ordinal measure for persons with atherosclerosis (range, 1-4). RESULTS: Of 474 nonnatural deaths, 453 (96%) were autopsied; 426 (90%) had coronary stenosis graded. In the ordinal-logistic model for trends in coronary artery disease grade (range, 0-4), the proportional odds assumption did not hold. In subsequent analysis as a dichotomous outcome (grades 0 vs 1-4), each artery exhibited a significant temporal decline in the proportion with any atherosclerosis. Conversely, for subjects with coronary artery disease grade 1-4, age- and sex-adjusted ordinal regression revealed no change over time in 2 arteries and statistically significant temporal increases in severity in 2 arteries. CONCLUSIONS: Findings suggest that efforts to prevent coronary artery disease onset have been relatively successful. However, statistically significant increases in the grade of atherosclerosis in 2 arteries among persons with coronary artery disease may be indicative of a major public health challenge.

Costs of venous thromboembolism associated with hospitalization for medical illness.

OBJECTIVES: To determine population-based estimates of medical costs attributable to venous thromboembolism (VTE) among patients currently or recently hospitalized for acute medical illness. STUDY DESIGN: Population-based cohort study conducted in Olmsted County, Minnesota. METHODS: Using Rochester Epidemiology Project (REP) resources, we identified all Olmsted County residents with objectively diagnosed incident VTE during or within 92 days of hospitalization for acute medical illness over the 18-year period of 1988 to 2005 (n=286). One Olmsted County resident hospitalized for medical illness without VTE was matched to each case for event date (±1 year), duration of prior medical history, and active cancer status. Subjects were followed forward in REP provider-linked billing data for standardized, inflation-adjusted direct medical costs (excluding outpatient pharmaceutical costs) from 1 year before their respective event or index date to the earliest of death, emigration from Olmsted County, or December 31, 2011 (study end date). We censored follow-up such that each case and matched control had similar periods of observation. We used generalized linear modeling (controlling for age, sex, preexisting conditions, and costs 1 year before index) to predict costs for cases and controls. RESULTS: Adjusted mean predicted costs were 2.5-fold higher for cases ($62,838) than for controls ($24,464) (P<.001) from index to up to 5 years post index. Cost differences between cases and controls were greatest within the first 3 months after the event date (mean difference=$16,897) but costs remained significantly higher for cases compared with controls for up to 3 years. CONCLUSIONS: VTE during or after recent hospitalization for medical illness contributes a substantial economic burden.

Contributions of increasing obesity and diabetes to slowing decline in subclinical coronary artery disease.

BACKGROUND: Our previous study of nonelderly adult decedents with nonnatural (accident, suicide, or homicide) cause of death (96% autopsy rate) between 1981 and 2004 revealed that the decline in subclinical coronary artery disease (CAD) ended in the mid-1990s. The present study investigated the contributions of trends in obesity and diabetes mellitus to patterns of subclinical CAD and explored whether the end of the decline in CAD persisted. METHODS AND RESULTS: We reviewed provider-linked medical records for all residents of Olmsted County, Minnesota, who died from nonnatural causes within the age range of 16 to 64 years between 1981 and 2009 and who had CAD graded at autopsy. We estimated trends in CAD risk factors including age, sex, systolic blood pressure, diabetes (qualifying fasting glucose or medication), body mass index, smoking, and diagnosed hyperlipidemia. Using multiple regression, we tested for significant associations between trends in CAD risk factors and CAD grade and assessed the contribution of trends in diabetes and obesity to CAD trends. The 545 autopsied decedents with recorded CAD grade exhibited significant declines between 1981 and 2009 in systolic blood pressure and smoking and significant increases in blood pressure medication, diabetes, and body mass index ≥30 kg/m(2). An overall decline in CAD grade between 1981 and 2009 was nonlinear and ended in 1994. Trends in obesity and diabetes contributed to the end of CAD decline. CONCLUSIONS: Despite continued reductions in smoking and blood pressure values, the previously observed end to the decline in subclinical CAD among nonelderly adult decedents was apparent through 2009, corresponding with increasing obesity and diabetes in that population.

Direct medical costs and source of cost differences across the spectrum of cognitive decline: a population-based study.

BACKGROUND: Objective cost estimates and source of cost differences are needed across the spectrum of cognition, including cognitively normal (CN), mild cognitive impairment (MCI), newly discovered dementia, and prevalent dementia. METHODS: Subjects were a subset of the Mayo Clinic Study of Aging stratified-random sampling of Olmsted County, MN, residents aged 70 to 89 years. A neurologist reviewed provider-linked medical records to identify prevalent dementia (review date = index). Remaining subjects were invited to participate in prospective clinical/neuropsychological assessments; participants were categorized as CN, MCI, or newly discovered dementia (assessment date = index). Costs for medical services/procedures 1-year pre-index (excluding indirect and long-term care costs) were estimated using line-item provider-linked administrative data. We estimated contributions of care-delivery site and comorbid conditions (including and excluding neuropsychiatric diagnoses) to between-category cost differences. RESULTS: Annual mean medical costs for CN, MCI, newly discovered dementia, and prevalent dementia were $6042, $6784, $9431, $11,678, respectively. Hospital inpatient costs contributed 70% of total costs for prevalent dementia and accounted for differences between CN and both prevalent and newly discovered dementia. Ambulatory costs accounted for differences between CN and MCI. Age-, sex-, education-adjusted differences reached significance for CN versus newly discovered and prevalent dementia and for MCI versus prevalent dementia. After considering all comorbid diagnoses, between-category differences were reduced (e.g., prevalent dementia minus MCI (from $4842 to $3575); newly discovered dementia minus CN (from $3578 to $711)). Following the exclusion of neuropsychiatric diagnoses from comorbidity adjustment, between-category differences tended to revert to greater differences. CONCLUSIONS: Cost estimates did not differ significantly between CN and MCI. Substantial differences between MCI and prevalent dementia reflected high inpatient costs for dementia and appear partly related to co-occurring mental disorders. Such comparisons can help inform models aimed at identifying where, when, and for which individuals proposed interventions might be cost-effective.

Direct medical costs attributable to venous thromboembolism among persons hospitalized for major operation: a population-based longitudinal study.

BACKGROUND: We estimated medical costs attributable to venous thromboembolism (VTE) among patients currently or recently hospitalized for major operation. METHODS: Using Rochester Epidemiology Project resources, we identified all Olmsted County, MN, residents with objectively diagnosed incident VTE within 92 days of hospitalization for major operation during an 18-year period, 1988-2005 (n = 355). One Olmsted County resident hospitalized for major operation without VTE was matched to each case on event date (±1 year), type of operation, duration of previous medical history, and active cancer status. Subjects were followed in Rochester Epidemiology Project provider-linked billing data for standardized, inflation-adjusted direct medical costs from 1 year before index (case's VTE event date and control's matched date) to earliest of death, emigration, or December 31, 2011. We used generalized linear modeling to predict costs for cases and controls and used bootstrapping methods to assess uncertainty and significance of mean adjusted cost differences. RESULTS: Adjusted mean predicted costs were more than 1.5-fold greater for cases ($55,956) than for controls ($32,718) (P ≤ .001) from index to up to 5 years postindex. Cost differences between cases and controls were greatest within the first 3 months after index (mean difference = $12,381). Costs were greater for cases than controls (mean difference = $10,797) from 3 months to up to 5 years postindex and together accounted for about half of the overall cost difference. CONCLUSION: VTE during or after recent hospitalization for major operation contributes a substantial economic burden; VTE-attributable costs are greatest in the initial 3 months but persist for up to 5 years.

Long-term stimulant medication treatment of attention-deficit/hyperactivity disorder: results from a population-based study.

The purpose of this study was to offer detailed information about stimulant medication treatment provided throughout childhood to 379 children with research-identified attention-deficit hyperactivity disorder (ADHD) in the 1976-1982 Rochester, MN, birth cohort. Subjects were retrospectively followed from birth until a mean of 17.2 years of age. The complete medical record of each subject was reviewed. The history and results of each episode of stimulant treatment were compared by gender, DSMIV subtype of ADHD, and type of stimulant medication. Overall, 77.8% of subjects were treated with stimulants. Boys were 1.8 times more likely than girls to be treated. The median age at initiation (9.8 years), median duration of treatment (33.8 months), and likelihood of developing at least one side effect (22.3%) were not significantly different by gender. Overall, 73.1% of episodes of stimulant treatment were associated with a favorable response. The likelihood of a favorable response was comparable for boys and girls. Treatment was initiated earlier for children with either ADHD combined type or ADHD hyperactive-impulsive type than for children with ADHD predominantly inattentive type and duration of treatment was longer for ADHD combined type. There was no association between DSM-IV subtype and likelihood of a favorable response or of side effects. Dextroamphetamine and methylphenidate were equally likely to be associated with a favorable response, but dextroamphetamine was more likely to be associated with side effects. These results demonstrate that the effectiveness of stimulant medication treatment of ADHD provided throughout childhood is comparable to the efficacy of stimulant treatment demonstrated in clinical trials.

Rethinking guidelines for VTE risk among nursing home residents: a population-based study merging medical record detail with standardized nursing home assessments.

BACKGROUND: Nursing home (NH) residents are at increased risk for both VTE and bleeding from pharmacologic prophylaxis. Construction of prophylaxis guidelines is hampered by NH-specific limitations with VTE case identification and characterization of risk. We addressed these limitations by merging detailed provider-linked Rochester Epidemiology Project (REP) medical records with Centers for Medicare and Medicaid Services Minimum Data Set (MDS) NH assessments. METHODS: This population-based nested case-control study identified all Olmsted County, Minnesota, residents with first-lifetime VTE October 1, 1998, through December 31, 2005, while a resident of an NH (N = 91) and one to two age-, sex-, and calendar year-matched NH non-VTE control subjects. For each NH case without hospitalization 3 months before VTE (n = 23), we additionally identified three to four nonhospitalized NH control subjects. REP and MDS records were reviewed before index date (VTE date for cases; respective REP encounter date for control subjects) for numerous characteristics previously associated with VTE in non-NH populations. Data were modeled using conditional logistic regression. RESULTS: The multivariate model consisting of all cases and control subjects identified only three characteristics independently associated with VTE: respiratory infection vs no infection (OR, 5.9; 95% CI, 2.6-13.1), extensive or total assistance with walking in room (5.6, 2.5-12.6), and general surgery (3.3, 1.0-10.8). In analyses limited to nonhospitalized cases and control subjects, only nonrespiratory infection vs no infection was independently associated with VTE (8.8, 2.7-29.2). CONCLUSIONS: Contrary to previous assumptions, most VTE risk factors identified in non-NH populations do not apply to the NH population. NH residents with infection, substantial mobility limitations, or recent general surgery should be considered potential candidates for VTE prophylaxis.

Familial risk of epilepsy: a population-based study.

Almost all previous studies of familial risk of epilepsy have had potentially serious methodological limitations. Our goal was to address these limitations and provide more rigorous estimates of familial risk in a population-based study. We used the unique resources of the Rochester Epidemiology Project to identify all 660 Rochester, Minnesota residents born in 1920 or later with incidence of epilepsy from 1935-94 (probands) and their 2439 first-degree relatives who resided in Olmsted County. We assessed incidence of epilepsy in relatives by comprehensive review of the relatives' medical records, and estimated age-specific cumulative incidence and standardized incidence ratios for epilepsy in relatives compared with the general population, according to proband and relative characteristics. Among relatives of all probands, cumulative incidence of epilepsy to age 40 was 4.7%, and risk was increased 3.3-fold (95% confidence interval 2.75-5.99) compared with population incidence. Risk was increased to the greatest extent in relatives of probands with idiopathic generalized epilepsies (standardized incidence ratio 6.0) and epilepsies associated with intellectual or motor disability presumed present from birth, which we denoted 'prenatal/developmental cause' (standardized incidence ratio 4.3). Among relatives of probands with epilepsy without identified cause (including epilepsies classified as 'idiopathic' or 'unknown cause'), risk was significantly increased for epilepsy of prenatal/developmental cause (standardized incidence ratio 4.1). Similarly, among relatives of probands with prenatal/developmental cause, risk was significantly increased for epilepsies without identified cause (standardized incidence ratio 3.8). In relatives of probands with generalized epilepsy, standardized incidence ratios were 8.3 (95% confidence interval 2.93-15.31) for generalized epilepsy and 2.5 (95% confidence interval 0.92-4.00) for focal epilepsy. In relatives of probands with focal epilepsy, standardized incidence ratios were 1.0 (95% confidence interval 0.00-2.19) for generalized epilepsy and 2.6 (95% confidence interval 1.19-4.26) for focal epilepsy. Epilepsy incidence was greater in offspring of female probands than in offspring of male probands, and this maternal effect was restricted to offspring of probands with focal epilepsy. The results suggest that risks for epilepsies of unknown and prenatal/developmental cause may be influenced by shared genetic mechanisms. They also suggest that some of the genetic influences on generalized and focal epilepsies are distinct. However, the similar increase in risk for focal epilepsy among relatives of probands with either generalized (2.5-fold) or focal epilepsy (2.6-fold) may reflect some coexisting shared genetic influences.

Long-term survival after traumatic brain injury: a population-based analysis controlled for nonhead trauma.

OBJECTIVE: To examine the contribution of co-occurring nonhead injuries to hazard of death after traumatic brain injury (TBI). PARTICIPANTS: A random sample of Olmsted County, Minnesota, residents with confirmed TBI from 1987 through 1999 was identified. DESIGN: Each case was assigned an age- and sex-matched, non-TBI "regular control" from the population. For "special cases" with accompanying nonhead injuries, 2 matched "special controls" with nonhead injuries of similar severity were assigned. MEASURES: Vital status was followed from baseline (ie, injury date for cases, comparable dates for controls) through 2008. Cases were compared first with regular controls and second with regular or special controls, depending on case type. RESULTS: In total, 1257 cases were identified (including 221 special cases). For both cases versus regular controls and cases versus regular or special controls, the hazard ratio was increased from baseline to 6 months (10.82 [2.86-40.89] and 7.13 [3.10-16.39], respectively) and from baseline through study end (2.92 [1.74-4.91] and 1.48 [1.09-2.02], respectively). Among 6-month survivors, the hazard ratio was increased for cases versus regular controls (1.43 [1.06-2.15]) but not for cases versus regular or special controls (1.05 [0.80-1.38]). CONCLUSIONS: Among 6-month survivors, accounting for nonhead injuries resulted in a nonsignificant effect of TBI on long-term mortality.

Billing code algorithms to identify cases of peripheral artery disease from administrative data.

OBJECTIVE: To construct and validate billing code algorithms for identifying patients with peripheral arterial disease (PAD). METHODS: We extracted all encounters and line item details including PAD-related billing codes at Mayo Clinic Rochester, Minnesota, between July 1, 1997 and June 30, 2008; 22 712 patients evaluated in the vascular laboratory were divided into training and validation sets. Multiple logistic regression analysis was used to create an integer code score from the training dataset, and this was tested in the validation set. We applied a model-based code algorithm to patients evaluated in the vascular laboratory and compared this with a simpler algorithm (presence of at least one of the ICD-9 PAD codes 440.20-440.29). We also applied both algorithms to a community-based sample (n=4420), followed by a manual review. RESULTS: The logistic regression model performed well in both training and validation datasets (c statistic=0.91). In patients evaluated in the vascular laboratory, the model-based code algorithm provided better negative predictive value. The simpler algorithm was reasonably accurate for identification of PAD status, with lesser sensitivity and greater specificity. In the community-based sample, the sensitivity (38.7% vs 68.0%) of the simpler algorithm was much lower, whereas the specificity (92.0% vs 87.6%) was higher than the model-based algorithm. CONCLUSIONS: A model-based billing code algorithm had reasonable accuracy in identifying PAD cases from the community, and in patients referred to the non-invasive vascular laboratory. The simpler algorithm had reasonable accuracy for identification of PAD in patients referred to the vascular laboratory but was significantly less sensitive in a community-based sample.

The absence of longitudinal data limits the accuracy of high-throughput clinical phenotyping for identifying type 2 diabetes mellitus subjects.

PURPOSE: To evaluate the impact of insufficient longitudinal data on the accuracy of a high-throughput clinical phenotyping (HTCP) algorithm for identifying (1) patients with type 2 diabetes mellitus (T2DM) and (2) patients with no diabetes. METHODS: Retrospective study conducted at Mayo Clinic in Rochester, Minnesota. Eligible subjects were Olmsted County residents with ≥1 Mayo Clinic encounter in each of three time periods: (1) 2007, (2) from 1997 through 2006, and (3) before 1997 (N = 54,283). Diabetes relevant electronic medical record (EMR) data about diagnoses, laboratories, and medications were used. We employed the HTCP algorithm to categorize individuals as T2DM cases and non-diabetes controls. Considering the full 11 years (1997-2007) as the gold standard, we compared gold-standard categorizations with those using data for 10 subsequent intervals, ranging from 1998-2007 (10-year data) to 2007 (1-year data). Positive predictive values (PPVs) and false-negative rates (FNRs) were calculated. McNemar tests were used to determine whether categorizations using shorter time periods differed from the gold standard. Statistical significance was defined as P < 0.05. RESULTS: We identified 2770 T2DM cases and 21,005 controls when the algorithm was applied using 11-year data. Using 2007 data alone, PPVs and FNRs, respectively, were 70% and 25% for case identification and 59% and 67% for control identification. All time frames differed significantly from the gold standard, except for the 10-year period. CONCLUSIONS: The accuracy of the algorithm reduced remarkably as data were limited to shorter observation periods. This impact should be considered carefully when designing/executing HTCP algorithms.

Asthma and proinflammatory conditions: a population-based retrospective matched cohort study.

OBJECTIVE: To determine the association between asthma and proinflammatory conditions. PARTICIPANTS AND METHODS: This population-based retrospective matched cohort study enrolled all asthmatic patients among Rochester, Minnesota, residents between January 1, 1964, and December 31, 1983. For each asthmatic patient, 2 age-and sex-matched nonasthmatic individuals were drawn from the same population. The asthmatic and nonasthmatic cohorts were followed forward in the Rochester Epidemiology Project diagnostic index for inflammatory bowel disease (IBD), rheumatoid arthritis (RA), diabetes mellitus (DM), and coronary heart disease (CHD) as outcome events. Data were fitted to Cox proportional hazards models. RESULTS: We identified 2392 asthmatic patients and 4784 nonasthmatic controls. Of the asthmatic patients, 1356 (57%) were male, and mean age at asthma onset was 15.1 years. Incidence rates of IBD, RA, DM, and CHD in nonasthmatic controls were 32.8, 175.9, 132.0, and 389.7 per 100,000 person-years, respectively; those for asthmatic patients were 41.4, 227.9, 282.6, and 563.7 per 100,000 person-years, respectively. Asthma was associated with increased risks of DM (hazard ratio, 2.11; 95% confidence interval, 1.43-3.13; P<.001) and CHD (hazard ratio, 1.47; 95% confidence interval, 1.05-2.06; P=.02) but not with increased risks of IBD or RA. CONCLUSION: Although asthma is a helper T cell type 2-predominant condition, it may increase the risks of helper T cell type 1-polarized proinflammatory conditions, such as CHD and DM. Physicians who care for asthmatic patients need to address these unrecognized risks in asthmatic patients.

Venous thromboembolism in nursing home residents: role of selected risk factors.

OBJECTIVES: To provide nursing home (NH)-specific estimates to assess whether venous thromboembolism (VTE) risk factors identified for the general population apply to NH residents. DESIGN: Population-based case-control study. SETTING: Olmsted County, Minnesota. PARTICIPANTS: All county residents with symptomatic objectively diagnosed incident VTE while resident in a NH from 1988 through 2000 (N = 182) and two age-, sex-, calendar-year-matched non-VTE Olmsted County NH residents per case (N = 364). MEASUREMENTS: Provider-linked medical records were reviewed to obtain information on active malignancy and recent hospitalization, surgery, trauma, or fracture as of index date (case's VTE date; respective provider registration date for controls). Risk factor prevalence and VTE-associated odds ratios (OR) were estimated and compared with previously obtained data for all Olmsted County residents from 1988 through 2000. For analyses, both groups were limited to individuals aged 65 and older. RESULTS: In NH residents, active malignancy, recent hospitalization, and recent surgery significantly increased VTE risk, but the magnitude of risk appeared much lower than general population estimates (e.g., for major surgery, OR = 2.5, 95% confidence interval (CI) = 1.4-4.3 for NH residents vs OR = 11, 95% CI = 7.0-17 for general population). In general, the prevalence of all evaluated VTE risk factors appeared much higher in NH controls than in general population controls. Thromboprophylaxis rates appeared higher for NH cases and controls than in the general population; disconcertingly, 47% of NH cases received prophylaxis. CONCLUSION: Although general population VTE risk factors (active cancer and recent hospitalization or surgery) can identify NH residents at higher risk for VTE, these exposures do not adequately stratify VTE risk for thromboprophylaxis recommendations. Further research into NH-specific risk factors and prophylaxis effectiveness is required.