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Left-truncated and interval-censored data, termed dynamic cohort data, arise in longitudinal studies with rolling admissions and only occasional follow-up. The authors compared four approaches for analyzing such data: a constant hazard model; maximum likelihood estimation with flexible parametric models; the midpoint method, in which the midpoint of the last negative and first positive test result is used in a Cox proportional hazards model that accounts for left truncation; and a semiparametric method that uses imputed failure times in the Cox model. By using a simulation study, they assessed the performance of these approaches under conditions that can arise in observational studies: changes in disease incidence and changes in the underlying population. The simulation results indicated that the constant hazard model and midpoint method were inadequate and that the flexible parametric model was useful when enough parameters were used in modeling the baseline hazard. The semiparametric method ensured correct parameter (odds ratio) estimation when the baseline hazard was misspecified, but the trade-off increased computational complexity. In this paper, a study of the incidence of human immunodeficiency virus in patients repeatedly tested for the virus at a sexually transmitted disease clinic in New Orleans, Louisiana, illustrates the methods used. [ABSTRACT FROM PUBLISHER]

The author reviews the history of the Tulane School of Public Health and Tropical Medicine. In 1912, Dr. Creighton Wellman published a groundbreaking paper entitled “The New Orleans School of Tropical Medicine and Hygiene,” outlining a clear plan for a new independent school of public health. He became the founding dean of the Tulane School of Hygiene and Tropical Medicine. Dr. Wellman had spent 9 years practicing medicine in Angola and graduated from the London School of Tropical Medicine before launching a career in tropical medicine in the United States. Tulane already had a formal course of hygiene established as early as 1881. The founding of Tulane School of Hygiene and Tropical Medicine was made possible by a gift from Samuel Zemurray, who would become the president of the United Fruit Company. In January of 1914, Dr. Wellman abruptly left New Orleans to live in Brazil. The school lost its independence in 1919 and again became part of the School of Medicine until 1967. The school initiated by Dr. Wellman is the foundation on which today's Tulane School of Public Health and Tropical Medicine is built. [ABSTRACT FROM PUBLISHER]

Leukocyte telomere length (LTL) is ostensibly a biomarker of human aging. Cross-sectional analyses have found that LTL is relatively short in a host of aging-related diseases. These studies have also provided indirect estimates of age-dependent LTL shortening. In this paper, the authors report findings of the first comprehensive longitudinal study of 450 whites and 185 African Americans in Louisiana (aged 31.4 and 37.4 years at baseline (1995–1996) and follow-up (2001–2006) examinations, respectively) participating in the Bogalusa Heart Study. Rate of change in LTL was highly variable among individuals, with some displaying a paradoxical gain in LTL during the follow-up period. The most striking observation was that age-dependent LTL shortening was proportional to LTL at baseline examination. At both baseline and follow-up examinations, African Americans had longer LTLs than whites, and smokers had shorter LTLs than nonsmokers. The longer LTL in African Americans than in whites explained in part the faster rate of LTL shortening observed among African Americans. These findings underscore the complexity of leukocyte telomere dynamics in vivo and suggest that determinants in addition to the “end-replication problem” contribute to telomere shortening in vivo. [ABSTRACT FROM AUTHOR]

The author regrets the failure to recognize the key role of the guest editors, Drs. Michel Ibrahim and Stephen Thacker, in the recent special issue celebrating the 100th anniversary of the Tulane University School of Public Health and Tropical Medicine.

The article presents a paper by Creighton Wellman, which was read before the Orleans Parish Medical Society, on March 1912.

In this study, the authors examined body image perception and body mass index (weight (kg)/height (m)2) among race-gender groups in a biracial (Black-White) population of young adults in Bogalusa, Louisiana. A mail-out survey was completed in 1994 by 3,698 (65%) participants aged 18.5-35 years in the Bogalusa Heart Study (mean age = 27.6 years). As part of the survey, body image perception was determined in terms of body shape representations from a figure rating scale. A body image discrepancy score was calculated from the difference between z-standardized values of body image perception and body mass index. A stepwise proportional odds model including the covariates income, employment, education, and physical activity was used to identify factors influencing lower perception of body shape. Mean body mass index was highest among Black females (p < 0.001). The odds of having a lower perception of body shape (vs. body mass index) were 1.72 times higher in Blacks (p < 0.001), 0.80 times lower in persons who were currently employed (p < 0.001), and 0.86 times lower in persons with a higher education (p = 0.032). Gender, income, and physical activity were not found to be significant predictors of body image perception (p > 0.05). The authors conclude that significant differences exist within racial groups concerning body image perception in relation to overweight status among young adults. This has implications for prevention and education programs. [ABSTRACT FROM AUTHOR]

A retrospective case-control study was performed in New Orleans, Louisiana, in 1985–1986 to test the hypotheses that 1) criminality is a risk factor for severe injury, and 2) the association between criminality and injury can be explained in terms of a common underlying factor—increased sensation-seeking tendencies. A total of 140 males with spinal cord injury were individually matched with 140 driver's license holders on age, race, sex, educational attainment, and zip code of residence and were interviewed by telephone. Criminality prior to spinal cord injury was measured by self-report and police records, and sensation seeking was measured by the Disinhibition and Boredom Susceptibility subscales of Zuckerman's Sensation-Seeking Scale (Form V). Those with spinal cord injuries were significantly more likely than controls to report a history of juvenile delinquency, adult criminality, and incarceration prior to the time of spinal cord injury. Statistically significant but modest differences were also found between cases and controls with respect to Disinhibition, Boredom Susceptibility, and the combined Sensation-Seeking Scale score. Matched-pairs logistic regression analysis indicated that the association between sensation seeking and spinal cord injury remained significant after controlling for criminality, with an estimated relative risk of 2.05 (95% confidence interval 1.67–2.53). However, the association between criminality and spinal cord injury also remained significant after controlling for sensation seeking (estimated relative risk = 2.04, 95% confidence interval 1.09–3.82). On the basis of these results, criminality and sensation seeking may be statistically significant but independent predictors of spinal cord injury. Am J Epidemiol 1996; 144: 463-72. [ABSTRACT FROM AUTHOR]