Worksite neighborhood and obesogenic behaviors: findings among employees in the Promoting Activity and Changes in Eating (PACE) trial.

BACKGROUND: Understanding mechanisms linking neighborhood context to health behaviors may provide targets for increasing lifestyle intervention effectiveness. Although associations between home neighborhood and obesogenic behaviors have been studied, less is known about the role of worksite neighborhood. PURPOSE: To evaluate associations between worksite neighborhood context at baseline (2006) and change in obesogenic behaviors of adult employees at follow-up (2007-2009) in a worksite randomized trial to prevent weight gain. METHODS: Worksite property values were used as an indicator of worksite neighborhood SES (NSES). Worksite neighborhood built environment attributes associated with walkability were evaluated as explanatory factors in relationships among worksite NSES, diet, and physical activity behaviors of employees. Behavioral data were collected at baseline (2005-2007) and follow-up (2007-2009). Multilevel linear and logistic models were constructed adjusting for covariates and accounting for clustering within worksites. Product-of-coefficients methods were used to assess mediation. Analyses were performed after study completion (2011-2012). RESULTS: Higher worksite NSES was associated with more walking (OR=1.16, 95% CI=1.03, 1.30, p=0.01). Higher density of residential units surrounding worksites was associated with more walking and eating five or more daily servings of fruits and vegetables, independent of worksite NSES. Residential density partially explained relationships among worksite NSES, fruit and vegetable consumption, and walking. CONCLUSIONS: Worksite neighborhood context may influence employees' obesogenic behaviors. Furthermore, residential density around worksites could be an indicator of access to dietary and physical activity-related infrastructure in urban areas. This may be important given the popularity of worksites as venues for obesity prevention efforts.

Bus stops and pedestrian-motor vehicle collisions in Lima, Peru: a matched case-control study.

OBJECTIVE: To evaluate the relationship between bus stop characteristics and pedestrian-motor vehicle collisions. METHODS: This was a matched case-control study where the units of study were pedestrian crossings in Lima, Peru. We performed a random sample of 11 police commissaries in Lima, Peru. Data collection occurred from February 2011 to September 2011. A total of 97 intersection cases representing 1134 collisions and 40 mid-block cases representing 469 collisions that occurred between October 2010 and January 2011, and their matched controls, were included. The main exposures assessed were presence of a bus stop and specific bus stop characteristics. The main outcome measure was occurrence of a pedestrian-motor vehicle collision. RESULTS: Intersections with bus stops were three times more likely to have a pedestrian-vehicle collision (OR 3.28, 95% CI 1.53 to 7.03), relative to intersections without bus stops. Formal and informal bus stops were associated with higher odds of a collision at intersections (OR 6.23, 95% CI 1.76 to 22.0 and OR 2.98, 1.37 to 6.49). At mid-block sites, bus stops on a bus-dedicated transit lane were also associated with collision risk (OR 2.36, 95% CI 1.02 to 5.42). All bus stops were located prior to the intersection, contrary to practices in most high-income countries. CONCLUSIONS: In urban Lima, the presence of a bus stop was associated with a threefold increase in risk of a pedestrian collision. The highly competitive environment among bus companies may provide an economic incentive for risky practices, such as dropping off passengers in the middle of traffic and jockeying for position with other buses. Bus stop placement should be considered to improve pedestrian safety.

The walking environment in Lima, Peru and pedestrian-motor vehicle collisions: an exploratory analysis.

OBJECTIVE: Pedestrians comprise 78% of the road fatalities in Peru. The objective of this study was to explore the relationship between the walking environment and pedestrian-motor vehicle collisions. METHODS: A matched case-control study was used to detect the odds of a pedestrian-motor vehicle collision at a pedestrian crossing location. Data were collected from 11 sampled police commissaries in Lima, Peru. RESULTS: In a multivariable model adjusting for vehicle and pedestrian flow, pedestrian collisions were less likely in the presence of a curb and sidewalk on both roadway sides (odds ratio [OR] = 0.19, 95% confidence interval [CI], 0.11-0.33) or a pedestrian barricade (OR = 0.11, 95% CI, 0.01-0.81). There was a greater risk of collisions for each street vendor present (OR = 2.82, 95% CI, 1.59-5.00) or whether any parked vehicles (OR = 3.67, 95% CI, 1.18-11.4) were present. CONCLUSIONS: Improving or addressing these potentially modifiable features of the walking environment could improve pedestrian safety in Lima and in similar urban settings in low- and middle-income countries.

Crash fatality and vehicle incompatibility in collisions between cars and light trucks or vans.

BACKGROUND: In crashes between a car and a light truck or van (LTV), car occupants are more likely to be killed than LTV occupants. The extent this is due to the greater harm imposed by LTVs on cars or the greater protection they offer their own occupants is not known. METHODS: We conducted a case-control study of collisions between two passenger vehicles in the USA during 1990-2008. Cases were all decedents in fatal crashes (N=157,684); one control was selected from each crash in a national probability sample of crashes (N=379,458). RESULTS: Adjusted for the type of vehicle they were riding in and other confounders, occupants of vehicles colliding with any type of LTVs (categorised as compact sport utility vehicles (SUV), full-size SUVs, minivans, full-size vans, compact pickups and full-size pickups) were at higher risk of death compared with occupants colliding with cars. Adjusted for the type of vehicle they crashed with and other confounders, occupants of LTVs in a collision with any vehicle were at lower risk of death compared with car occupants. Compared with a crash between two cars, the overall RR of death in a crash between any of the other 27 different combinations of vehicle types was 1.0 or greater, except for crashes between two full-size pickups, where the RR of death was 0.9. CONCLUSIONS: Although LTVs protect their own occupants better than cars do, LTVs are associated with an excess total risk of death in crashes with cars or other LTVs.

Crash fatality risk and unibody versus body-on-frame structure in SUVs.

BACKGROUND: In crashes between cars and SUVs, car occupants are more likely to be killed than if they crashed with another car. An increasing proportion of SUVs are built with unibody, rather than truck-like body-on-frame construction. Unibody SUVs are generally lighter, less stiff, and less likely to roll over than body-on-frame SUVs, but whether unibody structure affects risk of death in crashes is unknown. OBJECTIVE: To determine whether unibody SUVs differ from body-on-frame SUVs in the danger they pose to occupants of other vehicles and in the self-protection they offer to their own occupants. METHODS: Case-control study of crashes between one compact SUV and one other passenger vehicle in the US during 1995-2008, in which the SUV was model year 1996-2006. Cases were all decedents in fatal crashes, one control was selected from each non-fatal crash. FINDINGS: Occupants of passenger vehicles that crashed with compact unibody SUVs were at 18% lower risk of death compared to those that crashed with compact body-on-frame SUVs (adjusted odds ratio 0.82 (95% confidence interval 0.73-0.94)). Occupants of compact unibody SUVs were also at lower risk of death compared to occupants of body-on-frame SUVs (0.86 (0.72-1.02)). CONCLUSIONS: In two-vehicle collisions involving compact SUVs, unibody structure was associated with lower risk of death both in occupants of other vehicles in the crash, and in SUVs' own occupants.

Pedestrian signalization and the risk of pedestrian-motor vehicle collisions in Lima, Peru.

Safe walking environments are essential for protecting pedestrians and promoting physical activity. In Peru, pedestrians comprise over three-quarters of road fatality victims. Pedestrian signalization plays an important role managing pedestrian and vehicle traffic and may help improve pedestrian safety. We examined the relationship between pedestrian-motor vehicle collisions and the presence of visible traffic signals, pedestrian signals, and signal timing to determine whether these countermeasures improved pedestrian safety. A matched case-control design was used where the units of study were crossing locations. We randomly sampled 97 control-matched collisions (weighted N=1134) at intersections occurring from October, 2010 to January, 2011 in Lima. Each case-control pair was matched on proximity, street classification, and number of lanes. Sites were visited between February, 2011 and September, 2011. Each analysis accounted for sampling weight and matching and was adjusted for vehicle and pedestrian traffic flow, crossing width, and mean vehicle speed. Collisions were more common where a phased pedestrian signal (green or red-light signal) was present compared to no signalization (odds ratio [OR] 8.88, 95% Confidence Interval [CI] 1.32-59.6). A longer pedestrian-specific signal duration was associated with collision risk (OR 5.31, 95% CI 1.02-9.60 per 15-s interval). Collisions occurred more commonly in the presence of any signalization visible to pedestrians or pedestrian-specific signalization, though these associations were not statistically significant. Signalization efforts were not associated with lower risk for pedestrians; rather, they were associated with an increased risk of pedestrian-vehicle collisions.

Narcolepsy and the Sickness Impact Profile: A general health status measure.

OBJECTIVE: We characterized functional impact of narcolepsy on patients using a general health status measure, the Sickness Impact Profile (SIP). It has 136 items grouped into 12 categories and 2 dimensions. METHODS: We ascertained patients with physician-diagnosed narcolepsy in King County, Washington using multiple overlapping methods over four years starting July 2001. We recruited 226 patients (mean age 48 years, 65% female) who underwent in-person interviews and completed: Epworth Sleepiness Scale (ESS), Ullanlinna Narcolepsy Scale (UNS), and SIP. Linear regression was used to assess correlations between measures. RESULTS: Mean percent of total dysfunction was higher for psychosocial dimension (13.2) and independent categories (13.4) than physical dimension (5.0). Mean percent of total dysfunction in descending order for categories was: Sleep and Rest (23.6), Alertness Behavior (22.6), and Recreation and Pastimes (20.6). Ten items were endorsed by at least a third of all patients but only two of them concerned sleep. Unexpectedly, among the top ten items were, "My sexual activity is decreased," and "I forget a lot, for example, things that happened recently, where I put things, appointments." Percent of overall dysfunction on SIP (mean 10.3) was significantly correlated with ESS (r=0.36, p<0.001) and UNS (r=0.47, p<0.001). In this population-based sample, mean percent of total dysfunction on SIP in patients with narcolepsy (10.3) was higher than previously reported in the general population (3.6) and similar to that in other chronic disabling conditions. DISCUSSION: The SIP correlated with ESS and UNS, and captured unique aspects of the impact of narcolepsy on patients.

Prevalence of and risk factors for poor functioning after isolated mild traumatic brain injury in children.

This study aimed to determine the prevalence and predictors of poor 3 and 12 month quality of life outcomes in a cohort of pediatric patients with isolated mild TBI. We conducted a prospective cohort study of children and adolescents <18 years of age treated for an isolated mild TBI, defined as "no radiographically apparent intracranial injury" or "an isolated skull fracture, and no other clinically significant non-brain injuries." The main outcome measure was the change in quality of life from baseline at 3 and 12 months following injury, as measured by the Pediatric Quality of Life index (PedsQL). Poor functioning was defined as a decrease in total PedsQL score of >15 points between baseline and follow-up scores (at 3 and 12 months). Of the 329 patients who met inclusion criteria, 11.3% (95% CI 8.3-15.3%) at 3 months and 12.9% (95% CI 9.6-17.2%) at 12 months following injury had relatively poor functioning. Significant predictors of poor functioning included less parental education, Hispanic ethnicity (at 3 months following injury, but not at 12 months); low household income (at 3 and 12 months), and Medicaid insurance (at 12 months only). Children and adolescents sustaining a mild TBI who are socioeconomically disadvantaged may require additional intervention to mitigate the effects of mild TBI on their functioning.

Stability of clinical etiologic diagnosis in dementia and mild cognitive impairment: results from a multicenter longitudinal database.

Many new therapies for dementia target a specific pathologic process and must be applied early. Selection of specific therapy is based on the clinical etiologic diagnosis. We sought to determine the stability of the clinical etiologic diagnosis over time and to identify factors associated with instability. We identified 4141 patients with dementia or mild cognitive impairment who made at least 2 visits approximately a year apart to a dementia research center, receiving a clinical etiologic diagnosis on each visit. We assessed concordance of etiologic diagnoses across visits, κ-statistics, and transition probabilities among diagnoses. The primary clinical etiologic diagnosis remained stable for 91% of patients but with a net shift toward dementia with Lewy bodies and Alzheimer's disease. Lower diagnostic stability was significantly associated with older age, nonwhite race, milder disease at presentation, more underlying conditions contributing to cognitive decline, lack of a consistent spouse/partner informant, and being evaluated by different clinicians on different visits. Multistate Markov modeling generally confirmed these associations. Clinical etiologic diagnoses were generally stable. However, several readily ascertained characteristics were associated with higher instability. These associations may be useful to clinicians for anticipating when an etiologic diagnosis may be more prone to future change.

Disparities in disability after traumatic brain injury among Hispanic children and adolescents.

OBJECTIVE: To compare the extent of disability in multiple areas of functioning after mild, moderate, and severe traumatic brain injury (TBI) between Hispanic and non-Hispanic white (NHW) children. METHODS: This was a prospective cohort study of children aged <18 years treated for a TBI between March 1, 2007, and September 30, 2008. Hispanic (n = 74) and NHW (n = 457) children were included in the study. Outcome measures were disability in health-related quality of life, adaptive skills, and participation in activities 3, 12, 24, and 36 months after injury compared with preinjury functioning. We compared change in outcome scores between Hispanic and NHW children at each follow-up time. All analyses were adjusted for age, gender, severity and intent of injury, insurance, family function at baseline, parental education, and income. RESULTS: The health-related quality of life for all children was lower at all follow-up times compared with baseline. Although NHW children showed some improvement during the first 3 years after injury, Hispanic children remained significantly impaired. Significant differences were also observed in the domains of communication and self-care abilities after TBI. Differences between groups in scores for participation in activities were also present but were only significant 3 months after injury. CONCLUSIONS: Hispanic children with TBI report larger and long-term reductions in their quality of life, participation in activities, communication, and self-care abilities compared with NHW children. The reasons for these differences need to be better understood and interventions implemented to improve the outcomes of these children.

Differences in rate of functional decline across three dementia types.

BACKGROUND: The purpose of this study was to estimate differences in rates of functional decline in Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and vascular dementia (VaD) and whether differences vary by age or sex. METHODS: Data came from 32 U.S. Alzheimer's Disease Centers. The cohort of participants (n = 5848) were ≥60 years of age and had clinical dementia with a primary etiologic diagnosis of probable AD, DLB, or probable VaD; a Clinical Dementia Rating-Sum of Boxes score <16; and a duration of symptoms ≤10 years. Dementia diagnoses were assigned using standard criteria. Annual mean rate of change of the Functional Activities Questionnaire (FAQ) score was modeled using multiple linear regression with generalized estimating equations adjusted for demographics, comorbidities, years since onset, and cognitive status (mean follow-up = 2.0 years). RESULTS: FAQ declined more slowly over time in those with VaD compared with AD (difference in mean annual rate of change: -0.91; 95% confidence interval [CI]: -1.68, -0.14). VaD participants also declined at a slower rate than DLB participants, but this difference was not statistically significant (-0.61; 95% CI: -1.45, 0.24). There was no significant difference between DLB and AD. Within each group, rate of decline was more rapid for the youngest participants. CONCLUSIONS: In this sample, findings suggested that VaD patients declined in their functional abilities at a slower rate compared with AD patients and that there were no significant differences in rate of functional decline between patients with DLB compared with those with either AD or VaD. These results may provide guidance to clinicians about average expected rates of functional decline in three common dementia types.

Glycemic control associated with secure patient-provider messaging within a shared electronic medical record: a longitudinal analysis.

OBJECTIVE: To study differences in glycemic control and HbA1c testing associated with use of secure electronic patient-provider messaging. We hypothesized that messaging use would be associated with better glycemic control and a higher rate of adherence to HbA1c testing recommendations. RESEARCH DESIGN AND METHODS: Retrospective observational study of secure messaging at Group Health, a large nonprofit health care system. Our analysis included adults with diabetes who had registered for access to a shared electronic medical record (SMR) between 2003 and 2006. We fit log-linear regression models, using generalized estimating equations, to estimate the adjusted rate ratio of meeting three indicators of glycemic control (HbA1c <7%, HbA1c <8%, and HbA1c >9%) and HbA1c testing adherence by level of previous messaging use. Multiple imputation and inverse probability weights were used to account for missing data. RESULTS: During the study period, 6,301 adults with diabetes registered for access to the SMR. Of these individuals, 74% used messaging at least once during that time. Frequent use of messaging during the previous calendar quarter was associated with a higher rate of good glycemic control (HbA1c <7%: rate ratio, 1.26 [95% CI, 1.15-1.37]) and a higher rate testing adherence (1.20 [1.15-1.25]). CONCLUSIONS: Among SMR users, recent and frequent messaging use was associated with better glycemic control and a higher rate of HbA1c testing adherence. These results suggest that secure messaging may facilitate important processes of care and help some patients to achieve or maintain adequate glycemic control.

Outcomes in pediatric surgery by hospital volume: a population-based comparison.

PURPOSE: The volume-outcome relationship has not been well-defined in pediatric surgery. Our aim was to determine the association between hospital-volume and outcomes for common procedures in children. METHODS: Retrospective population-based cohort study of patients <18 years of age hospitalized between 1989 and 2009 for common surgical procedures in Washington State. The association between annual hospital case volume and post-operative outcomes (readmission and reoperation within 30-days, post-operative complications) was assessed using multivariate logistic regression. RESULTS: The three most common procedures over the study period were appendectomy (n = 36,525), skin and soft tissue debridement (n = 9,813), and pyloromyotomy (n = 3,323). A greater proportion of patients with comorbidities were treated at higher-volume hospitals. After adjustment, outcomes did not differ significantly across hospital-volume quartiles except that debridement patients had lower odds of readmission (OR = 0.63, 95 % CI 0.46-0.88) and re-operation (OR = 0.53, 95 % CI 0.35-0.81) at medium-high-volume compared with high-volume centers. CONCLUSIONS: This work suggests that risks of readmission and post-operative complications for common procedures may be similar across hospital-volume categories, but appropriate risk-stratification is essential. In order to optimize safety, we must identify the resources required for low-, medium-, and high-risk surgical patients, and implement these standards into practice.

Will the light truck bumper height-matching standard reduce deaths in cars?

BACKGROUND: In a collision between a car and a sport utility vehicle (SUV) or pickup truck, car occupants are more likely to be killed than if they crashed with another car. Some of the excess risk may be due to the propensity of SUVs and pickups with high bumpers to override the lower bumpers in cars. To reduce this incompatibility, particularly in head-on collisions, in 2003 automobile manufacturers voluntarily established a bumper height-matching standard for pickups and SUVs. OBJECTIVE: To assess whether height-matching bumpers in pickups and SUVs were associated with the risk of death in either car occupants or pickup and SUV occupants. METHODS: Case-control study of collisions between one car and one SUV or pickup in the US during 2000-2008, in which the SUV or pickup was model year 2000-2006. Cases were all decedents in fatal crashes; one control was selected from each crash in a national probability sample of crashes. FINDINGS: Occupants of cars that crashed with SUVs or pickups with height-matching bumpers may be at slightly reduced risk of death compared to those that crashed with other SUVs or pickups (adjusted odds ratio: 0.83 (95% confidence interval 0.61-1.13)). There was no evidence of a reduction in risk in head-on crashes (1.09 (0.66-1.79)). In crashes in which the SUV or pickup struck the car on the side, height-matched bumpers were associated with a reduced risk of death (0.68 (0.48-0.97)). Occupants of SUVs and pickups with height-matching bumpers may also be at slightly reduced risk of death (0.91 (0.64-1.28)). CONCLUSIONS: Height-matching bumpers were associated with a reduced risk of death among car occupants in crashes in which SUVs or pickups struck cars in the side, but there was little evidence of an effect in head-on crashes. The new bumper height-matching standard may not achieve its primary goal of reducing deaths in head-on crashes, but may modestly reduce overall deaths in crashes between cars and SUVs or pickups because of unanticipated benefits to car occupants in side crashes, and a possible beneficial effect to SUV and pickup occupants.

Reversion from mild cognitive impairment to normal or near-normal cognition: risk factors and prognosis.

OBJECTIVES: We sought to identify characteristics of individuals with mild cognitive impairment (MCI) that are associated with a relatively high probability of reverting back to normal cognition, and to estimate the risk of future cognitive decline among those who revert. METHODS: We first studied 3,020 individuals diagnosed with MCI on at least 1 visit to an Alzheimer's Disease Center in the United States. All underwent standardized Uniform Data Set evaluations at their first visit with an MCI diagnosis and on a subsequent visit, about 1 year later, at which cognitive status was reassessed. Multiple logistic regression was used to identify predictors of reverting from MCI back to normal cognition. We then estimated the risk of developing MCI or dementia over the next 3 years among those who had reverted, compared with individuals who had not had a study visit with MCI. RESULTS: About 16% of subjects diagnosed with MCI reverted back to normal or near-normal cognition approximately 1 year later. Five characteristics assessed at the first MCI visit contributed significantly to a model predicting a return to normal cognition: Mini-Mental State Examination (MMSE) score, Clinical Dementia Rating (CDR) score, MCI type, Functional Activities Questionnaire (FAQ) score, and APOE ε4 status. Survival analysis showed that the risk of retransitioning to MCI or dementia over the next 3 years was sharply elevated among those who had MCI and then improved, compared with individuals with no history of MCI. CONCLUSIONS: Even in a cohort of patients seen at dementia research centers, reversion from MCI was fairly common. Nonetheless, those who reverted remained at increased risk for future cognitive decline.

Incidence of disability among children 12 months after traumatic brain injury.

OBJECTIVES: We examined the burden of disability resulting from traumatic brain injuries (TBIs) among children younger than 18 years. METHODS: We derived our data from a cohort study of children residing in King County, Washington, who were treated in an emergency department for a TBI or for an arm injury during 2007-2008. Disabilities 12 months after injury were assessed according to need for specialized educational and community-based services and scores on standardized measures of adaptive functioning and social-community participation. RESULTS: The incidence of children receiving new services at 12 months was about 10-fold higher among those with a mild TBI than among those with a moderate or severe TBI. The population incidence of disability (defined according to scores below the norm means on the outcome measures included) was also consistently much larger (2.8-fold to 28-fold) for mild TBIs than for severe TBIs. CONCLUSIONS: The burden of disability caused by TBIs among children is primarily accounted for by mild injuries. Efforts to prevent these injuries as well as to decrease levels of disability following TBIs are warranted.

Preventive services in veterans in relation to disability.

Veterans with disabilities are at an increased risk of secondary impairments and may have difficulty accessing preventive services; accessibility may differ between Veterans who do and do not receive care at Department of Veterans Affairs (VA) facilities. We used data from the 2003 and 2004 Behavioral Risk Factor Surveillance System surveys to evaluate associations between disability and receipt of preventive services in Veterans. Veterans with a disability were more likely to have received influenza vaccinations (VA users and nonusers), pneumococcal vaccinations (VA nonusers: p < 0.001; VA users: p = 0.073), weight management counseling (VA nonusers: p < 0.001; male VA users: p < 0.001), lower gastrointestinal (GI) endoscopy (VA nonusers: 50-64 yr, p = 0.03; VA users: ≥65 yr, p = 0.085), mammography (VA users: p = 0.097), and serum cholesterol screening (VA nonusers: p < 0.001). Receipt was similar by disability status for fecal occult blood test (FOBT), lower GI endoscopy (VA users: 50-64 yr), human immunodeficiency virus testing, and cervical cancer screening. For no measure was there significantly lower receipt in those with versus without a disability, although there was marginal evidence in VA nonusers for overall colorectal cancer screening (i.e., lower GI endoscopy or FOBT: p = 0.063). Among Veterans, having a disability did not appear to be a barrier to receiving appropriate preventive care.

Persistence of disability 24 to 36 months after pediatric traumatic brain injury: a cohort study.

This study examined the outcome of 0- to 17-year-old children 36 months after traumatic brain injury (TBI), and ascertained if there was any improvement in function between 24 and 36 months. Controls were children treated in the emergency department for an arm injury. Functional outcome 36 months after injury was measured by the Pediatric Quality of Life Inventory (PedsQL), the self-care and communication subscales of the Adaptive Behavior Assessment Scale-2nd edition (ABAS-II), and the Child and Adolescent Scale of Participation (CASP). At 36 months after TBI, those with moderate or severe TBI continued to have PedsQL scores that were 16.1 and 17.9 points, respectively, lower than at baseline, compared to the change seen among arm injury controls. Compared to the baseline assessment, children with moderate or severe TBI had significantly poorer functioning on the ABAS-II and poorer participation in activities (CASP). There was no significant improvement in any group on any outcomes between 24 and 36 months. Post-injury interventions that decrease the impact of these deficits on function and quality of life, as well as preventive interventions that reduce the likelihood of TBI, should be developed and tested.

Effects of experience and commercialisation on survival in Himalayan mountaineering: retrospective cohort study.

OBJECTIVES: To determine whether previous Himalayan experience is associated with a decreased risk of climbing death, and whether mountaineers participating in commercial expeditions differ in their risk of death relative to those participating in traditional climbs. DESIGN: Retrospective cohort study. SETTING: Expeditions in the Nepalese Himalayan peaks, from 1 January 1970 to the spring climbing season in 2010. PARTICIPANTS: 23,995 non-porters venturing above base camp on 39,038 climbs, 23,295 on 8000 m peaks. OUTCOME: Death. RESULTS: After controlling for use of standard route, peak, age, season, sex, summit success, and year of expedition, increased Himalayan experience was not associated with a change in the odds of death (odds ratio 1.00, 95% confidence interval 0.96 to 1.05, P = 0.904). Participation in a commercial climb was associated with a 37% lower odds of death relative to a traditional venture, although not significantly (0.63, 0.37 to 1.09, P = 0.100). Choice of peak was clearly associated with altered odds of death (omnibus P<0.001); year of expedition was associated with a significant trend toward reduced odds of death (0.98, 0.96 to 0.99, P = 0.011). CONCLUSIONS: No net survival benefit is associated with increased Himalayan experience or participation in a traditional (versus commercial) venture. The incremental decrease in risk associated with calendar year suggests that cumulative, collective knowledge and general innovation are more important than individual experience in improving the odds of survival.

Association between posttraumatic stress, depression, and functional impairments in adolescents 24 months after traumatic brain injury.

The degree to which postinjury posttraumatic stress disorder (PTSD) and/or depressive symptoms in adolescents are associated with cognitive and functional impairments at 12 and 24 months after traumatic brain injury (TBI) is not yet known. The current study used a prospective cohort design, with baseline assessment and 3-, 12-, and 24-month followup, and recruited a cohort of 228 adolescents ages 14-17 years who sustained either a TBI (n = 189) or an isolated arm injury (n = 39). Linear mixed-effects regression was used to assess differences in depressive and PTSD symptoms between TBI and arm-injured patients and to assess the association between 3-month PTSD and depressive symptoms and cognitive and functional outcomes. Results indicated that patients who sustained a mild TBI without intracranial hemorrhage reported significantly worse PTSD (Hedges g = 0.49, p = .01; Model R(2) = .38) symptoms across time as compared to the arm injured control group. Greater levels of PTSD symptoms were associated with poorer school (η(2) = .07, p = .03; Model R(2) = .36) and physical (η(2) = .11, p = .01; Model R(2) = .23) functioning, whereas greater depressive symptoms were associated with poorer school (η(2) = .06, p = .05; Model R(2) = .39) functioning.