Evaluation of risk factors and health outcomes among persons with asthma.

OBJECTIVE: To examine risk factors associated with healthcare utilization in Arizona Medicaid patients with asthma.

METHODS: Data were obtained from Arizona Medicaid between 1/1/2002 and 12/31/2003. Inclusion criteria consisted of persons with an asthma diagnosis (ICD9-CM 493.XX), 5 to 62 years of age; and were new users of inhaled-corticosteroids (ICS), combination ICS+long-acting beta-agonist, or leukotriene-modifiers. Factors examined included age, geographic location (urban/rural), race/ethnicity (White, non-Hispanic Black, Hispanic, other), medication adherence, pre-period short-acting beta-agonist use (SABA), and co-morbidities. Utilization measures examined included SABA use; exacerbations measured by hospital visits; and asthma-related and total healthcare costs. Analyses for utilization measures were performed using negative binomial, logistic regression, and generalized linear modeling gamma-family, log-link, respectively.

RESULTS: A total of 3,013 subjects met inclusion/exclusion criteria and had a mean age (+/-SD) of 24.7 +/-13.7 years. Urban residents were 55% more likely to have an exacerbation than rural residents (odds ratio-OR 0.45, 95%CI: 0.27-0.78). Age (years 18 to 62) was a significant predictor for SABA use (incidence rate ratio-IRR 1.22, 95% CI: 1.06-1.41); and exacerbations (OR 2.07, 95% CI: 1.28-3.38). Mean predicted asthma cost was $530 (95% CI: $461-608) for ages 5 to 17, $702 (95% CI $600-822) for ages 18 to 39), and $583 (95% CI $468-726) for ages 40 to 62. Males were 46% less likely to have an exacerbation than females (OR 0.54, 95% CI: 0.31-0.94). Exacerbations were not different between race/ethnicity categories. Predicted mean asthma-related costs were not different between Whites ($591, 95% CI: $509-686), Blacks ($638, 95% CI: $499-815), or Hispanics ($535, 95% CI: $466-614).

CONCLUSIONS: Results of these analyses found urban areas had higher rates of asthma-related hospital visits compared to rural counties, but no difference in asthma-costs between urban and rural areas which may suggest rural exacerbations may be more costly or severe. Persons with asthma aged 18 to 62 had higher rates of asthma-related emergency-room visits/hospitalizations than those aged 5 to 18. Persons 18 to 39 years of age had higher costs than person 5 to 17 or 40 to 62. Race/ethnicity in this population was not a significant predictor of outcomes or asthma-related costs.