The main purpose of this study was “to determine whether groups reported in the past as having higher rates of morbidity and mortality, such as black patients and those living in urban environments, were at risk because of their socioeconomic status (in which case, we should have found little variation in their treatment despite different race and residence) or because of other factors (eg, variations in treatment despite equivalent socioeconomic status and insurance).” Furthermore, the analysis focused on variations in the quantity and types of drugs used to treat asthma and variability by race, age, and/or residence.

The study population was defined on a yearly basis from 1980 to 1986 and included Michigan Medicaid enrollees between the ages of 5 and 14 years. An average of 5,858 cases of childhood asthma per year were identified in the Computerized Online Medicaid Pharmaceutical Analysis and Surveillance System (COMPASS).

The results indicated a statistically significant gap between black and white patients with respect to the average number of asthma drug prescriptions filled per year, per asthmatic. After stratifying by sex and residence, blacks persistently had lower rates across all age groups (between the ages of 5-9, 4.9 prescriptions for black asthmatics compared to 6.2 for white asthmatics; ages of 10-14, 5.0 for blacks vs. 7.1 for whites). Upon evaluating differences in the prescribing patterns between the black and white population, black patients were less likely to receive steroids than whites (9.8 vs. 17.8, respectively), less likely to be prescribed an adrenergic inhaler (19.4 vs. 25, respectively), but blacks were significantly more likely to receive fixed-combination prescription (43.5 for blacks vs. 27.1 for whites). In fact, “fixed-combination products received far greater use in urban blacks and, to a lesser extent, in urban whites, than in their rural counterparts.” The authors note that “these recipients received the least number of prescription drugs for their asthma but had the highest rates of care utilization.”

The authors conclude that the “implications of these findings” are “important because inadequate therapy may lead to undesirable outcomes, such as hospitalization, increased emergency departments visits, or perhaps even a fatality.”

Given that the study population shared a similar socioeconomic status and availability of insurance, the differences in prescribed medication cannot be explained by financial barriers, which are often offered as a possible explanation for the disparities. Furthermore, as explained by the authors, “in a previous study of hospitalization in this same Medicaid population, we found higher annual rates of hospitalizations in all blacks when compared with the white population,” thus indicating a worse morbidity rate among the group less likely to be treated with the latest, highly effective drugs. More disturbing is the higher rate of prescription of fixed combination products, which “had long been discouraged by the academic community.” As early as 1978, the efficacy of these drugs was dubious and by 1984 “nearly all asthma combinations were listed as less than effective.” By 1981, Medicaid would no longer pay for these prescriptions. However, “for our Medicaid study population…the prevalence of use continued to remain high in urban blacks until 1984.” The authors then ask “why did these physicians continue prescribing these products?” They offer the following potential explanations: (1) “a group of patients may exhibit product preference,” (2) “physicians practicing in a poor urban area may not have been exposed to changes in therapeutic recommendations, and thus continued to prescribe fixed-combination products well after they had become unacceptable to other prescribers,” and (3) “there is also a matter of convenience.” In a busy practice, it is much easier to write a prescription for a combination rather than two or three single entity products.”