Prescribing rates of HMV in the 37 healthcare sectors of the Catalan Health Service were compared from billing data from 2008 to 2011. Crude accumulated activity rates (per 100 000 population) were calculated using systematic component of variation (SCV) and empirical Bayes (EB) methods. Standardized activity ratios (SAR) were described using a map of healthcare sectors.
A crude rate of 23 HMV prescriptions per 100 000 population was observed. Rates increase with age and have increased by 39%. Statistics measuring variation not due to chance show a high variation in women (SCV=0.20 and EB=0.30) and in men (SCV=0.21 and EB=0.40), and were constant over time. In a multilevel Poisson model, hospitals with a respiratory medicine unit were associated with a greater number of cases (beta=0.68, P<.0001).
High variability in prescribing HMV can be explained, in part, by the attitude of professionals toward treatment and accessibility to specialist centers with a respiratory medicine unit. Analysis of administrative data and variability mapping help identify unexplained variations and, in the absence of systematic records, are a feasible way of tracking treatment.