Did recent expansions in Medicaid narrow socioeconomic differences in hospitalization rates of infants?

OBJECTIVE. TO test whether socioeconomic differences in the ratio of infant hospitalizations to births, a proxy for infant hospitalization rates, and hospital lengths of stay for infants narrowed between 1988 and 1992: a peri od of large increases in the numbers of low-income infants enrolled in Medi caid. RESEARCH DESIGN. Before and after comparison of socioeconomic differences i n the ratio of infant hospitalizations to births tie, infant hospitalizatio n rates) and lengths of stay between 1988 and 1992. By use of ICD-9 codes, hospitalizations were categorized as mandatory or discretionary. The differ ence between the 2 is that discretionary hospitalizations are potentially a voidable with appropriate primary care. Difference-in-differences technique s were used to assess the differential change in the rates of hospitalizati ons and lengths of stay for infants from low-income, compared with high-inc ome, zip codes. SETTING AND PARTICIPANTS. Discharges of infants <2 years of age at 326 nonf ederal, short-term, general, and other specialty hospitals in 8 states. OUTCOME MEASURES. Ratios of discretionary and mandatory hospitalizations to births (ie, hospitalization rates) and hospital lengths of stay of infants <2 years of age. RESULTS. Infants from the poorest zip codes had ratios of discretionary hos pitalizations to births ((discretionary hospitalization rate) that were 3.1 % points higher than infants from the wealthiest zip codes and ratios of ma ndatory hospitalizations to births (mandatory hospitalization rates) that w ere 0.2% points higher. Poor versus nonpoor differences in lengths of stay were 0.3 and 1.9 days for discretionary and mandatory hospitalizations, res pectively. No narrowing in the socioeconomic gradients about ratios of hosp italizations to births tie, rates of hospitalization) or lengths of stay wa s observed. CONCLUSIONS. Expansions in the Medicaid program from 1988 to 1992 did not r esult in a decrease in ratios of discretionary hospitalizations to births t ie, discretionary hospitalization rate) or hospital length of stay for infa nts from low-income areas.