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OBJECTIVES: This study identified age-related differences in diagnosis and progression of HIV by analyzing a nationally representative sample of HIV-infected adults under care in the United States. METHODS: We compared older (> or = 50 years) and younger participants stratified by race/ethnicity. Regression models controlled for demographic, therapeutic, and clinical factors. RESULTS: Older non-Whites more often had HIV diagnosed when they were ill. Older and younger patients were clinically similar. At baseline, however, older non-Whites had fewer symptoms and were less likely to have AIDS, whereas at follow-up they had a trend toward lower survival. CONCLUSIONS: Later HIV diagnosis in non-Whites merits public health attention; clinical progression in this group requires further study. [ABSTRACT FROM AUTHOR]

Two types of reporting inconsistency for sexual initiation were analyzed--event occurrence and its timing--using data from two waves of the National Longitudinal Study of Adolescent Health (Add Health). Overall, 11.1% of those who reported they were sexually active at the time of first interview denied this at the subsequent one. Males of each race/ethnic group had higher percentages of inconsistency than their female counterparts. Being older, not living with parents, or having a highly educated mother was negatively associated with rescinding. Among those reporting sexual experience at both interviews, only 22.2% reported the same date of first sex. On average, teens revised their age at first sex to older ages, and boys, especially African American boys, had large variability in reporting dates, as did teens with lower verbal ability. Seven strategies for resolving inconsistent reports are presented and implications for substantive findings are discussed.

We examined the determinants of nonmarital fertility, focusing on the effects of other life-course events: education, marriage, marital dissolution, and marital fertility. Since these determinants are potentially endogenous, we modeled the processes that generate them jointly with nonmarital fertility and accounted for the sequencing of events and the unobserved correlations across processes. The results showed that the risk of nonmarital conception increases immediately after leaving school and that the educational effects are less pronounced for black women than for other women. The risk is lower for previously married women than for never-married women, even controlling for age, but this reduction is significant only for black women. The more children a woman already has, the lower her risk of nonmarital childbearing, particularly if the earlier children were born during a previous marriage. Ignoring endogeneity issues seriously biases the estimates of several substantively important effects.

Data from the National Longitudinal Study of the High School Class of 1972 are used to estimate a series of models of entry into marriage, entry into cohabitation, and nonmarital pregnancy. Our models account explicitly for the endogeneity of one outcome as a predictor of another by taking into account both heterogeneity across individuals due to unmeasured factors that may affect all these outcomes and the correlation in the unmeasured factors across processes. We find that these heterogeneity components are strongly and positively related across the outcomes. Women who are more likely to cohabit, marry, or become pregnant while unmarried are also more likely to do each of the others. Although black and white women differ in the likelihood of these behaviors, the interrelations of the behaviors are quite similar across groups.

Administrative records from the Medicare Program of the Health Care Financing Administration provide a valuable source of information for research on medical and public policy issues. This administrative database contains information on utilization of covered medical services, diagnoses, episodes of illness, and Medicare-covered costs of health care. Combining such data with information from national surveys on health status, demographics, and socioeconomic attributes substantially expands the scope of potential research questions that can be addressed. This article discusses the benefits and difficulties of linking Medicare administrative data with survey data and provides brief summaries of five national surveys of elderly U.S. citizens. These surveys can be valuable resources for examining the health status and life experiences of the Medicare population.

Expenditures for prescription drugs are not covered by Medicare and are thus a potential source of large out-of-pocket expenditures for elderly persons. This study, using a new data source, the 1990 Elderly Health Supplement to the Panel Study of Income Dynamics (PSID), demonstrates that, among elderly persons, insurance coverage for drugs reduces the fraction of household income spent on prescription drugs by 50 percent. Groups most likely to benefit from insurance coverage are elderly women and those with common chronic conditions, low incomes, and rural residences.

In this paper we discuss a number of hypotheses about motives for intergenerational transfers within the family. We use data on time and money transfers between generations in Malaysia, where there is neither Social Security nor Medicare, to explore these hypotheses empirically. We find evidence supporting the hypotheses that children are an important source of old age security and that old age security is, in part, children's repayment for parental investments in their education. This repayment is partly a function of the children's income and, in the case of females, a function of their spouse's income. We also find evidence supporting the hypotheses that parents and children engage in the exchange of time help for money.

Prior literature has shown that married men live longer than unmarried men. Possible explanations are that marriage protects its incumbents or that healthier men select themselves into marriage. Protective effects, however, introduce the possibility of adverse selection: Those in poor health have incentive to marry. In this paper we explore the role of health in explaining mortality and marriage patterns, and distinguish protective effects from two types of selection effects. We find adverse selection on the basis of health (unhealthy men tend to (re)marry sooner) and positive selection on the basis of unmeasured factors that both promote good health and encourage marriage.

Infant and child mortality rates have dropped sharply for all ethnic groups in Malaysia between 1950 and 1988, but persistent ethnic differences remain. In this article we assess the contribution of several potential reasons both for the decline and the remaining differences between the Malay and Chinese sub-populations. Increased use of health inputs is found to explain a substantial part of the decline, but increased education of mothers, and income growth are also important. Longer spacing between births, and, higher average age at birth as a result of lower fertility and higher age at marriage provide only a marginal direct contribution to the fall in mortality. We find that lower mortality among the Chinese is accounted for by their higher incomes and greater propensty to purchase medical care. We also control for self-selection among users of medical care, and find that those who use health care in Malaysia tend to be subject to higher-than-average risks.

Married couples who began their relationship by cohabiting appear to face an increased risk of marital dissolution, which may be due to self-selection of more dissolution-prone individuals into cohabitation before marriage. This paper uses newly developed econometric methods to explicitly address the endogeneity of cohabitation before marriage in the hazard of marital disruption by allowing the unobserved heterogeneity components to be correlated across the decisions to cohabit and to end a marriage. These methods are applied to data from the National Longitudinal Study of the High School Class of 1972. We find significant heterogeneity in both cohabitation and marriage disruption, and discover evidence of self-selection into cohabitation.

This paper is concerned with the relationship between child mortality and the use of health care. We develop a simultaneous model of fetal and postnatal mortality risks and input demand equations for prenatal medical care and institutional delivery. This model is applied to retrospective data from Peninsular Malaysia covering 1950-1988. The results show that prenatal medical care and institutional delivery have strong beneficial effects on child survival probabilities, and that these effects are substantially underestimated when adverse self-selection among users of health care is ignored. The effectiveness of prenatal health care in Malaysia improved until 1980, and then deteriorated. We find that the risk of infant and child mortality is not independent of fetal survival, but show that ignoring selective fetal survival introduces only mild biases in infant and child mortality estimation. Higher infant and child mortality rates among young mothers are partly explained by their lower likelihood of purchasing health care.

Married couples with children appear to be less likely to end their marriages than childless couples, especially when the children are young. Although this suggests that children affect the chances that their parents will divorce, the process may not be so simple: the chances that the marriage will last also may affect couples' willingness to make the commitment to the marriage implied by having children. This paper uses data from the Panel Study of Income Dynamics (PSID) to test the hypothesis that the risk of disruption faced by a married woman affects the chances that she will conceive and bear a child. The model used takes into account the simultaneous relationships between marital dissolution and marital fertility by including the hazard of disruption as a predictor of timing and likelihood of marital conception, and by including the results of previous fertility decisions as predictors of disruption of the marriage. We find that the hazard of disruption has strong negative effects on the hazard of marital childbearing, lengthening the intervals between births and decreasing the chances that a child will be born. This effect appears to be strongest for women who have had at least one child, either before or during the current marriage, although it is also large for childless women. Explicitly including the hazard of disruption in models of marital childbearing has sizable and important effects on many predictors of fertility.

"This paper develops an approach to simultaneity among hazard equations which is similar in spirit to simultaneous Tobit models. It introduces a class of continuous time models which incorporates two forms of simultaneity across related processes--when the hazard rate of one process depends (1) on the hazard rate of another process or (2) on the actual current state of or prior outcomes of a related multi-episode process. This paper also develops an approach to modeling the notion of 'multiple clocks' in which one process may depend on the duration of a related process, in addition to its own. Maximum likelihood estimation is proposed based on specific parametric assumptions. The model is developed in the context of and empirically applied to the joint determination of marital duration and timing of marital conceptions.", (excerpt)

Between 1963 and 1970 public programs were introduced to reduce inequalities in access to medical care. We examined differentials in surgical utilization among socioeconomic groups in 1970 as well as changes between 1963 and 1970. Multivariate analysis of National Health Interview Survey data indicated that large increases in surgical utilization occurred among disadvantaged groups: the aged, lower educated and nonwhites in urban areas. Some differential by race and residence remains, but is strongly related to income. Income had a large positive effect on surgical utilization, but this effect was less strong in 1970 than in 1963. Education had a negative effect on surgical utilization. Eleven surgical procedures were selected and scaled on indexes of "complexity," "urgency" and "necessity." These indexes do not vary among demographic groups that have significant differences in surgical utilization. However, lower-income groups utilized to a lesser extent procedures rated lowest on the necessity scale.