1998-2002 Update on "Causes of death in autism".
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
Robert M Shavelle
Publications and source records attributed to Robert M Shavelle.
Trends in life expectancy after spinal cord injury.
OBJECTIVE: To investigate whether there have been improvements in survival after spinal cord injury (SCI) over time, both in the critical first 2 years after injury and in the longer term. DESIGN: Pooled repeated observations analysis of person-years. For each person-year, the outcome variable is survival and mortality, and the explanatory variables include age, level and grade of injury, and calendar year (the main focus of the analyses). The method can be viewed as a generalization of proportional hazards regression. SETTING: Model spinal cord injury systems and hospital SCI units across the United States. PARTICIPANTS: Persons (N=30,822) admitted to a Spinal Cord Injury Model Systems facility a minimum of 1 day after injury. Only persons over 10 years of age and known not to be ventilator dependent were included. These persons contributed 323,618 person-years of data, with 4980 deaths, over the 1973 to 2004 study period. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Survival. RESULTS: Other factors being equal, over the last 3 decades there has been a 40% decline in mortality during the critical first 2 years after injury. However, the decline in mortality over time in the post-2-year period is small and not statistically significant. CONCLUSIONS: The absence of a substantial decline in mortality after the first 2 years postinjury is contrary to widely held impressions. Nevertheless, the finding is based on a large database and sensitive analytic methods and is consistent with previous research. Improvements in critical care medicine after spinal cord injury may explain the marked decline in short-term mortality. In contrast, although there have no doubt been improvements in long-term rehabilitative care, their effect in enhancing the life span of persons with SCI appears to have been overstated.
Adolescent↗
Worklife after traumatic spinal cord injury.
OBJECTIVE: To develop predictive models to estimate worklife expectancy after spinal cord injury (SCI). DESIGN: Inception cohort study. SETTING: Model SCI Care Systems throughout the United States. PARTICIPANTS: 20,143 persons enrolled in the National Spinal Cord Injury Statistical Center database since 1973. INTERVENTION: Not applicable. MAIN OUTCOME MEASURE: Postinjury employment rates and worklife expectancy. RESULTS: Using logistic regression, we found a greater likelihood of being employed in any given year to be significantly associated with younger age, white race, higher education level, being married, having a nonviolent cause of injury, paraplegia, ASIA D injury, longer time postinjury, being employed at injury and during the previous postinjury year, higher general population employment rate, lower level of Social Security Disability Insurance benefits, and calendar years after the passage of the Americans with Disabilities Act. CONCLUSIONS: The likelihood of postinjury employment varies substantially among persons with SCI. Given favorable patient characteristics, worklife should be considerably higher than previous estimates.
Adult↗
Computing exact excess death rates from a published mortality study.
We wish to estimate the associated excess death rate (EDR) or mortality ratio (MR) from a published study of persons with a given medical condition. This requires computation of the expected mortality in the study population. If age- and sex-specific person years of data are available, this task is straightforward. Most often, however, we have only descriptive statistics--percentage male, average and standard deviation of age--at the beginning of follow up. We show here how this limited information can be used to compute an exact EDR or other quantities of interest.
Age Distribution↗
Reproducibility and variability of activated clotting time measurements in the cardiac catheterization laboratory.
The objective of this study was to characterize the reproducibility and variability in the measurement to the activated clotting time (ACT) when performed on two different types of instruments, the HemoTec ACT (Medtronic) and the Hemochron 801 (International Technidyne). The ACT has evolved into the most common point-of-care test used in the cardiac catheterization lab to manage patient heparinization. Since the test has not been standardized, different systems frequently produce different results under the same clinical conditions. Duplicate paired ACT tests (n = 885) from 359 patients were performed on both instruments. Prothrombin times (PT) and activated partial thromboplastin times (aPTT) were also determined on subsets of these same samples (PT = 533; aPTT = 487). The performance and relationships between the two tests were determined using a variety of statistical analytical techniques. The average difference between the ACT devices was only 8 sec, yet more than 60% of the measurements varied by more than 10%. Over one-fourth of measurements varied by more than 20%. The reproducibility to the HemoTec instrument was superior to the Hemochron instrument across the entire range of ACTs measured (mean coefficient of variation 2.4% +/- 3.1% vs. 7.2% +/- 6.1% for HemoTec and Hemochron, respectively; P < 0.00001; range = 65-555 sec). The relationship between the two ACTs was nonlinear. In therapeutic ranges used for interventional procedures (200-350 sec), HemoTec and Hemochron ACTs are not comparable to one another. Statistical comparative analysis indicated that the HemoTec ACT has better overall performance.
Adolescent↗
Mortality and causes of death in persons with Down syndrome in California.
This study investigated mortality and causes of death between 1988 and 1999 in 14781 persons (6702 female) with Down syndrome in California, comparing age, sex, ethnicity, and other factors. Mean age at the start of follow-up was 14 years 8 months (SD 14y 10mo). During the study period 600 persons died. The standardized mortality ratio (SMR) for the population was 5.5. Blacks were at greater risk than whites, Hispanics, or Asians (relative risk = 1.5). Mortality declined during the period, especially for children with congenital heart defects. Leukemia (SMR = 17), respiratory illnesses (SMR = 27), congenital anomalies (SMR = 72), and circulatory diseases (SMR = 5.3) accounted for most of the excess mortality. With the exception of leukemia, cancer mortality was not different from that of the general population.
Adolescent↗
Estimation of future mortality rates and life expectancy in chronic medical conditions.
Estimates of old-age mortality are necessary for the construction of life tables and computation of life expectancy, and are essential in the growing area of life insurance for the elderly. Two common assumptions are that either the excess death rate (EDR) or the relative risk (RR) stays constant with increasing age. It is known, however, that for most medical conditions the former underestimates the risk and the latter overestimates it. A third popular method is that of rating up: a subject is said to be "rated up k years" if his future mortality rates are assumed to be those of a person in the general population who is k years older. It is shown here that this method generally leads to gross overestimates of old-age mortality. We consider two less-commonly used models, log-linear declining relative risk (LDR) and constant proportional life expectancy (PLE), and compare them to the methods of constant EDR, constant RR and rating up. Although slightly more complicated to employ than the other methods, both LDR and PLE generally give better estimates of mortality and life expectancy. When mortality rates for chronic conditions are known within a certain age range, and estimates outside of the range are required, the LDR and PLE methods may be preferable to the more familiar methods of constant EDR, constant RR, or rating up.
Adult↗
Prognosis for ambulation in cerebral palsy: a population-based study.
OBJECTIVES: To determine independent predictors of ambulation among children with cerebral palsy and to develop a simple tool that estimates the probability that a child will walk. METHODS: In a retrospective study of all children with cerebral palsy who were not yet walking at 2 to 3(1/2) years of age, while receiving services from the California Department of Developmental Services during the years 1987-1999, we analyzed medical and functional data obtained annually by Department of Developmental Services physicians and social workers. Using logistic regression analyses, we determined independent predictors of a child's ability to walk well alone at least 20 feet, without assistive devices, by age 6. We then estimated the probabilities of walking at various levels of ability over time, using multistate survival analysis. RESULTS: Of 5366 study subjects, 2295 (43%) were evaluated at age 6; 12.8% could walk independently and 18.4% walked with support. Independent predictors of successful ambulation included early motor milestones such as sitting (odds ratio: 12.5; 95% confidence interval: 5.8-27.2) and pulling to a stand (odds ratio: 28.5; 95% confidence interval: 13.4-60.4) when compared with lack of rolling at age 2, cerebral palsy type other than spastic quadriparesis (odds ratio: 2.2; 95% confidence interval: 1.5-3.1), and preserved visual function (odds ratio: 2.4; 95% confidence interval: 1.1-5.4). Our ambulation charts depict the probability of remaining nonambulatory, transitioning to 1 of 3 possible ambulatory states, or expiring at all subsequent ages through age 14. CONCLUSION: The ambulation charts provide a simple straightforward way to estimate the probability that a child with cerebral palsy who is nonambulatory at 2 to 3 12 years of age will eventually walk with or without support.
Analysis of Variance↗
Life expectancy after traumatic brain injury.
Explore the source record for details and available documents.
Adolescent↗
Remote symptomatic epilepsy: does seizure severity increase mortality?
OBJECTIVE: To investigate the excess mortality due to remote symptomatic epilepsy, taking account of frequency and type of seizures. METHODS: The authors compared mortality in persons with (n = 8,156) and without (n = 72,526) history of epilepsy in a 1988 to 1999 California population of persons with mild developmental disabilities. Subjects had traumatic brain injury, cerebral palsy, Down syndrome, autism, or no identifiable condition. There were 506,204 person-years of data, with 1,523 deaths. Excess death rates and standardized mortality ratios were computed for the persons in the study with epilepsy, relative to those in the study without epilepsy. Controlled comparisons were made using logistic regression on person-years. RESULTS: Compared to subjects with no epilepsy, the excess mortality was six (deaths per 1,000 persons per year) for persons with a recent (<12 months) history of status epilepticus, five for a recent history of generalized tonic-clonic seizure, three for a recent history of nonconvulsive seizures, and less than one for a history of epilepsy but no recent events. Proportion in remission and excess mortality showed no change over the 12-year study period. CONCLUSIONS: Persistent seizures are associated with increased mortality in remote symptomatic epilepsy. Mortality is highest among individuals with status epilepticus or generalized convulsions.
Adolescent↗
Comparative mortality of persons with mental retardation in California 1980-1999.
Explore the source record for details and available documents.
Adolescent↗
Ethnic differences in coronary atherosclerosis.
OBJECTIVES: The study was done to evaluate whether ethnic differences exist in the prevalence of coronary artery calcification (CAC), and to determine whether differences in calcification correlate with the degree of coronary obstruction. BACKGROUND: Electron beam tomography (EBT) can be used to quantitate the amount of CAC and assist in prognostication of future cardiac events. It is unclear whether ethnic differences in coronary mortality are related to differences in the prevalence of coronary obstruction and CAC. METHODS: A total of 782 symptomatic subjects underwent both EBT and angiography. A 50% luminal narrowing defined an angiographic obstruction. RESULTS: We observed substantial ethnic differences in prevalence of both CAC and angiographic stenosis. In whites (n = 453), prevalence of CAC (score >0) was 84%, and significant obstruction on angiogram was 71%. Compared with whites, blacks (n = 108) had a significantly lower prevalence of CAC (62%, p < 0.001) and angiographic disease (49%, p < 0.01). Hispanics (n = 177) also had a lower prevalence of CAC (71%, p < 0.001) and angiographic obstruction (58%, p < 0.01). Asians (n = 44) were not significantly different in regard to CAC (73%, p = 0.06) or angiographic stenosis (64%, p = 0.30). These ethnic differences remained after simultaneously controlling (by use of multiple logistic regression) for age, gender and cardiac risk factors. CONCLUSIONS: As compared with whites, blacks and Hispanics had significantly lower prevalence of CAC and obstructive coronary disease. Ethnic differences in risk-factor profiles do not explain these differences. This study demonstrated that whites have a higher atherosclerotic burden than blacks and Hispanics, independent of risk-factor differences among symptomatic patients referred for angiography.
Adult↗
Electron beam tomography and angiography: sex differences.
BACKGROUND: We sought to study a large cohort of symptomatic women to determine the clinical use of electron beam tomography (EBT), with evaluation of the sensitivity and specificity of obstructive coronary disease and the differences between premenopausal and postmenopausal cohorts. METHODS: Patients who underwent angiography for evaluation of coronary artery disease (CAD) and EBT within 3 months were enrolled. Receiver operating characteristic curves were used to establish relationships between EBT calcium scores and angiographic disease. RESULTS: We studied 1120 symptomatic patients, 387 women and 733 men. We found no significant differences with respect to sensitivity for obstructive disease (96% in men and women). However, women had a significantly higher specificity (46% in men versus 57% in women; P =.01). The area under the curves for coronary calcium score predicting angiographic disease was 0.85 for all patients and 0.84 in women. Evaluation of scores on the basis of age revealed a 14.4-year lag between men and women. One hundred thirty-five women had negative EBT study results (score, zero; no calcium present), with 6 with single-vessel disease and 129 with normal coronaries or nonobstructive disease only (negative predictive value, 96%). CONCLUSION: EBT may have a great value in evaluation of women with possible CAD. The high sensitivity and high negative predictive value may serve as the basis for a new diagnostic approach to filter symptomatic women with suspected CAD before coronary angiography.
Calcinosis↗