Stephen R. Dearwater

The epidemiology of low back pain in an adolescent population.

We assessed the prevalence of low back pain (LBP) in a cohort of 1242 adolescents (aged 11 through 17) currently participating in a 4-year prospective study of medically treated injuries. Overall, 30.4% of the adolescents reported LBP. The impact of LBP in adolescents was considerable, with one third resulting in restricted activity and 7.3% seeking medical attention. Life-table analysis demonstrated that by age 15, the prevalence of LBP increased to 36%. There were few differences by gender or race. These results suggest that LBP in adolescents is a serious public health problem.

The epidemiology of leisure physical activity in an adolescent population.

A cohort of 1245 adolescents, 12-16 yr old and participating in a prospective study of risk factors for injury, were surveyed annually to assess past year leisure physical activity. This report describes the development and reproducibility of the questionnaire and provides the descriptive epidemiology of leisure physical activity in adolescents. The questionnaire was self-administered twice, a year apart, and had a 1 yr test-retest rank order correlation of 0.55. The past year estimate of leisure activity was also shown to be related to fitness (rho = -0.37), which was defined as the time needed to complete a 1-mile run. Males reported significantly more activity than females (P < 0.05) and whites reported more activity than nonwhites (P < 0.05). However, socioeconomic status was not found to be a determinant of activity levels in either males or females. In females, a negative association between activity and age was found (P < 0.05); however, this association was not evident in males. In summary, an activity questionnaire has been developed and was shown to be both reproducible and feasible. Therefore, it was used to examine habitual leisure physical activity patterns of adolescents.

Physical activity and the initiation of high-risk health behaviors in adolescents.

The association of physical activity to the initiation of health risk behaviors was examined in a 3-yr prospective study of a population-based cohort of 1245 adolescents aged 12-16 yr. Four hundred thirty-seven students (35% of the cohort) were identified at baseline via self-report survey as never having smoked cigarettes, consumed alcohol, used marijuana, or carried a weapon. Three measures of physical activity were obtained at baseline: leisure-time physical activity (LTPA), level of aerobic fitness (AF), and participation in competitive athletics. Significant associations, with notable gender differences, were observed between physical activity and the initiation of cigarette smoking and alcohol use. The cumulative proportion of male students initiating alcohol use was 48%, 42%, and 24% for high, moderate, and low LTPA, respectively (P < 0.01). Males who participated in competitive athletics were significantly more likely than nonathletes to initiate alcohol use (44% vs 17%, P < 0.01). The cumulative proportion of female students initiating cigarette use was 10%, 23%, and 22% for high, moderate, and low LTPA, respectively (P < 0.05) and 7%, 28%, and 16% for high, moderate, and low AF, respectively (P < 0.05). No association was found between physical activity and weapon carrying. These results indicate that in this cohort of adolescents, the most active or most fit females were less likely to initiate cigarette smoking. In contrast, the most active males or males who participated in competitive athletics appeared more at-risk for initiating alcohol consumption than their less active counterparts.

Activity in the spinal cord-injured patient: an epidemiologic analysis of metabolic parameters

Individuals with traumatic spinal cord injury (SCI) represent a population with extreme inactivity. The purpose of the current research was to investigate the metabolic differences between extremely inactive disabled individuals (SCI sedentary group), active disabled individuals (SCI athletes), and able-bodied individuals. Fasting morning blood samples were obtained for the determination of high density lipoprotein cholesterol (HDLc) subfractions, glucose, and insulin. The sedentary SCI group was comprised of 77 consecutive male admissions to a rehabilitation center. The 17 SCI athletes were recruited prior to competition at the annual National Wheelchair Games. Total HDLc and both its subfractions were significantly lower (P less than 0.01) in the male SCI sedentary population than in the SCI athletes or able-bodied controls. HDL2 was significantly elevated (P less than 0.01) in the SCI athlete compared to the SCI sedentary group (42.7 vs 34.1 mg X dl-1) and was similar to the control population (46.1 mg X dl-1). Glucose levels were similar in the two SCI groups but were both significantly lower (P less than 0.05) than in the able-bodied controls. These data suggest that the extreme inactivity observed in disabled populations is associated with lower HDLc concentrations and presumably an increase in coronary heart disease risk if these values were to persist over time. Additionally, it appears that physical activity is associated with increases in total HDLc, primarily through the HDL2 subfraction. Glucose and insulin were similar for both SCI groups despite the marked difference in activity levels, suggesting that these parameters may not be associated with activity.

Assessment of physical activity in inactive populations.

The ability to index activity objectively in disabled or impaired activity populations is critical for our understanding of the long-term health consequences of reduced activity. The current research employed the large-scale integrated activity monitor as an objective measure of free living daily activity in 28 subjects with traumatic spinal cord injury. All the spinal cord-injured subjects wore the monitors for 2 d while in-patients at a rehabilitation center. The results indicated that the instruments can accurately index individual physical activity levels in this population, which has drastically reduced activity. Furthermore, group differences in activity were discriminated where paraplegic activity (mean, 32.0 counts X h-1) was significantly greater than quadriplegic activity (mean, 15.1 counts X h-1) (P less than 0.01) despite the markedly low activity levels. The results thus indicate that activity sensors can index individual activity levels at the very low end of the activity spectrum.

Echocardiographic left ventricular mass and physical activity: quantification of the relation in spinal cord injured and apparently healthy active men.

To assess the relation of echocardiographic left ventricular (LV) mass to reported physical activity, 2 groups of subjects with widely different physical activity levels were evaluated: 50 men with spinal cord injuries and 166 apparently healthy, active men. Multivariate analysis revealed that reported physical activity was a significant independent predictor of LV mass index (LV mass/body surface area) in both injured patients and healthy, active subjects after controlling for age and blood pressure. The relation between LV mass index and physical activity (linear regression) was similar for both groups; LV mass index = 0.00321 (physical activity) + 82.8 and LV mass index = 0.00335 (physical activity) +88.4 for patients and healthy active subjects, respectively. These results suggest that physical activity as assessed by self-report is associated with echocardiographically detectable differences in LV mass in groups with widely divergent physical activity levels. In addition, for each of these groups 1,000 kcal/week of physical activity apparently results in a change of approximately 3 g/m2 in LV mass index. This information may have practical use for correction of LV mass for the effects of physical activity.

Establishment of accurate incidence rates for head and spinal cord injuries in developing and developed countries: A capture-recapture approach

Prevention of head and spinal cord injuries is defined as a reduction in the incidence of these disabilities. Accurate incidence data are fundamental to any prevention program. The current approaches toward determining incidence rates for head and spinal cord injuries are summarized. Previous research has focused on passive surveillance systems and population-based registries. An alternative system for monitoring the incidence of head injuries is discussed that uses a surveillance methodology called capture-recapture. This method employs multiple population-based sources to identify cases and uses the cases that overlap between the sources to estimate the degree of undercount in the population. This estimate in turn is used to produce an ascertainment-corrected incidence estimate. Through the use of methods such as capture-recapture, accurate monitoring of the incidence of head and spinal injuries across developing and developed countries is indeed feasible.

Identifying homes with inadequate smoke detector protection from residential fires in Pennsylvania

With data from the Center for Disease Controls Behavioral Risk Factor Surveillance System, we estimated the prevalence of homes with inadequate smoke detector protection from residential fires in Pennsylvania and identified the characteristics of these homes in an effort to identify useful prevention strategies for Pennsylvania and other regions with similar characteristics. Homes with inadequate smoke detector protection from residential fires were defined on three levels. Eight percent (95% CL = 6.8, 8.6) of homes lacked any installed smoke detectors, 14% (95% CL = 12.8, 15) lacked smoke detectors installed on the same floor where they slept, and 28% (95% CL = 26.6, 29.6) were found to engage in unsafe smoke detector practices. The strong predictors of unsafe smoke detector practices determined from logistic regression included black, non-Hispanic homes (OR = 1.53), homes with annual household income of less than +20,000 (OR = 1.29), and those with no children younger than 5 years old (OR = 1.55). These findings should assist policy makers in planning residential fire prevention programs for Pennsylvania, which has yet to meet the Healthy People 2000 objective regarding fire prevention.

Surveillance of serious recreational injuries: a capture-recapture approach.

Serious injury from sport and recreation is a leading cause of morbidity and mortality in the United States. Historically, occurrences of diseases with substantial public health impact have been monitored via surveillance systems in order to obtain information concerning the frequency with which the diseases occur. Surveillance leads to efforts that identify risk factors, and eventually, control measures to reduce the incidence of disease. Currently, the surveillance of sports injury represents only limited coverage in the U.S. It is important to begin discussions regarding approaches toward the development of surveillance of these injuries. Methods based upon the communicable disease surveillance model could potentially be used to monitor serious sports injuries. One method of surveillance, using the statistical approach of capture-mark-recapture, is presented as an example by which a national system of surveillance of serious sports injury could be established.