Ronald L. Williams

Measuring the effectiveness of perinatal medical care.

An outcome-based index of the effectiveness of perinatal care was empirically tested using 3,441,448 linked birth-death records. In order to construct the index, an expected perinatal mortality rate was computed for 504 California hospitals, based on each newborns birth weight, sex, race, and plurality. The index was then defined as the ratio of the observed mortality rate to that expected. From the sixteen-fold range observed in the unadjusted rates, a two-fold variation could be attributed to differentials in the efficacy of medical care. The remainder resulted from differences in patient risk and from binomial variations. The observed--expected ratio was observed to be significantly correlated with a number of traditional indicators of medical care quality. Multiple regression techniques revealed that the mortality ratio was significantly lower in larger delivery services, in urban hospitals, in hospitals performing above-average numbers of cesarean sections in those recording Apgar scores, and in hospitals having higher specialist-to-generalist ratios. Conversely, the ratio was significantly higher in hospitals with larger percentages of Spanish-surnamed mothers and in private proprietary hospitals. By separating the index into its observed and expected components, the regression model accounted for 82 per cent of the variance in the observed perinatal mortality rates.

Cesarean section in California—1960 through 1975

The cesarean section rate has been rising in California since 1965. In this article, we describe the trend in cesarean section rates in California from 1960 to 1975 in relation to maternal and infant variables. Approximately proportionate increases in cesarean section rates by infant birth weight and maternal race were found. Cesarean section rates for women under 20 years of age and for those of first parity have risen proportionately more than rates for other age and parity groups. We also found that cesarean section rates for births at gestational ages exceeding 42 weeks have risen proportionately more than rates for births at other gestational ages. Maternal mortality ratios associated with cesarean section were twice those associated with noncesarean births for the years 1973, 1974, and 1975. Possible explanations of the current cesarean section rate include an increase in indications for the procedure, use of the fetal monitor, and the current medical-legal climate. The potential problems that cesarean section may create for the mother and infant are higher rates of iatrogenic prematurity and respiratory distress and of maternal morbidity and mortality.

Intrauterine growth curves: Intra- and international comparisons with different ethnic groups in California

Abstract The position of the United States in international comparisons of infant mortality rates has deteriorated in recent years. It is suggested here that this result may in part be due to relatively poorer levels of maternal nutrition and to less favorable socioeconomic environments. Historical studies of the effects of wartime-induced famine as well as pathological investigations have shown that maternal undernutrition results in lower weights for newborn infants. Low birth weight in turn has a profound effect on subsequent perinatal loss. Maternal nutrition can be thought of as a constraint on fetal growth and comparisons of intrauterine growth curves may indicate the effects of nonoptimal nutritional standards. Because the effect of ethnic group membership on the growth of the fetus is not well-understood, it is important to hold that variable constant if environmental effects are to be isolated. A technique is presented, using a massive set of vital records, for making such intrauterine growth comparisons. The results suggest that low birth weight, resulting from relatively inferior socioeconomic and environmental conditions, may explain a large proportion of the relatively high infant mortality rate observed in the United States, and that preventive measures may be effective means for lowering pregnancy wastage.

Validity of insurance information on California birth certificates.

OBJECTIVESnThis study assessed the validity of health insurance information on California birth certificates.nnnMETHODSnInsurance information from birth certificates and linked face-to-face interviews was compared for 7428 postpartum women in California.nnnRESULTSnThere was excellent agreement between insurance information in birth certificate and interview data, especially when capitated plans were grouped with all other private coverage. Analyses using both data sources produced similar estimates of the likelihood of untimely prenatal care according to type of insurance coverage.nnnCONCLUSIONSnBirth certificate data including insurance information appear to be an appropriate resource for examining both the extent of coverage for maternity care and associations between prenatal care use and insurance status.

Monitoring perinatal mortality rates: California, 1970 to 1976

Recent developments have emphasized the need to monitor perinatal mortality statistics by small geographic areas. A method is presented which separates county-specific perinatal mortality rates into a component reflective of socioeconomic, behavioral, and environmental variables, and a component that relates more directly to hospital-based intra- and postpartum care. Major differences in geographic variations were observed between the crude rate and the two components. An arbitrary index of the need for perinatal health services was created by combining the two components with the number of perinatal deaths in each county. Although there are some obvious limitations, the index serves as a useful guidepost for monitoring perinatal mortality on a statewide basis.

Explaining a Health Care Paradox

The paradox of a statistically weak linkage between physician density and measures of health based on outcome has recently received much attention because of its importance to health planning policy. It is demonstrated here that the linkage is stronger than indicated by previous studies if the statistical model is more carefully specified. A single case-type is chosen so that the impact of physician services is not filtered out by the aggregation process and a quantitative variable measuring case severity is derived. When statistical techniques are applied to correct for case-risk and for the inherent heteroscedasticity in observed mortality rates across states and time, the positive effect of physician density on health is shown to be statistically highly significant. Thus the apparently paradoxical findings in previous studies may be a result of failing to correct not only for differences in case severity but also for variations in sample errors. Also, even though the magnitude of physician impact is small compared to non-medical variables, an exploratory estimate of the impact of government programs focused on prevention suggests that present allocations between prevention and treatment may approximate optimality.