The prevalence of low risk asthma in adults in a large health care program: An audit for diagnostic accuracy

Abstract

Rationale We determined the prevalence in 2003 of reversible airflow obstruction (RAO) or methacholine hyper-reactivity (MHR) in adults, age 18–64, with physician diagnosed and/or treated low-risk asthma during 2001 identified by the Kaiser Permanente San Diego (KPSD) Asthma Case Identification Database (ACID). Methods ACID identifies all patients who received 2+ asthma medications or any asthma care in KPSD. In 2001 KPSD had 326,950 adult members, 12315 (3.76%) were in ACID, and 7460 (60.6%) were low risk. Low-risk was defined as no emergency visits or hospitalizations, <3 courses of oral steroids per year, <12 beta agonist canisters per year, <3 different prescribers per year, and a primary care provider. 400 random low-risk patients were sequentially invited to undergo, between 1–30-03 and 9–9-03, an asthma questionnaire, allergy tests, physical exam, documentation of RAO by acute beta-agonist treatment and/or Advair® 500/50 2 puffs daily for 2 weeks, and/or MHR testing. Medical records for all 400 were reviewed. Results 106 (26.5%) individuals started and 81 (76.4%) completed the work-up. Asthma based on at least a 12% improvement in FEV1 after albuterol or Adviar® or MHR was verified in 51 (48.1%) and of those 33 (64.3%) were allergic. There was no correlation between BMI and asthma. In 2001, the California Health Interview Survey (CHIS) determined 7.4% (95% CI 6.5 - 8.3) of San Diego County residents had active asthma. Conclusions Asthma documented by ACID is less common than reported by CHIS. Over 1/3 of adults requiring care for the asthma can not be confirmed to have RAO or MHR 2 years later.