BACKGROUND AND OBJECTIVE: Studies from the US and Canada observed changes in antihypertensive prescribing patterns in accordance with Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) study findings immediately after the study's publication, but little is known about the impact of ALLHAT in Italy. The objective of this study was to examine antihypertensive prescribing patterns in Regione Emilia-Romagna (RER), Italy, following the publication of the ALLHAT main results.
METHODS: We conducted a time series analysis using automated pharmacy data of approximately 4 million RER residents between 1 January 2000 and 31 December 2003. We computed monthly relative percentages of prescriptions for all antihypertensive medications and separately for all new antihypertensives defined as no recorded antihypertensive use in the previous year. A stepwise auto-regressive forecasting model based on data prior to the ALLHAT publication was used to estimate predicted relative percentages for the 12 months following the ALLHAT publication. Observed and predicted values were compared.
RESULTS AND DISCUSSION: Use of thiazide-type diuretics showed a general increasing trend over the study period, but the difference between the observed and predicted values reached statistical significance only for new prescriptions in October 2003 (3.71% vs. 2.32%; P = 0.0170). The relative percentage of new angiotensin-converting enzyme inhibitor and angiotensin receptor blocker (ACE/ARB) prescriptions was higher than predicted for the months May to August 2003 (P < 0.05), but no significant differences were observed for total ACE/ARB prescriptions. Modest changes in patterns of prescribing of calcium channel blockers and alpha-blockers were observed.
CONCLUSION: We found little evidence that the ALLHAT study had an impact on antihypertensive prescribing patterns in RER in the year following their publication.
JoshuaJGagne3⃣The problem occurs only with truly persistent users -- i.e., those who will continue to be exposed until they die -- and not with long-term exposures as long as a steady-state of starting and stopping is reached. See box plot in 1⃣ for unbiased fixed 180-day exposure estimate.
JoshuaJGagne1⃣Bias is small but apparent when 10% of patients are persistent users (see figure: biased odds ratio = 1.11; true OR = 1.00). Bias is sizable (OR = 1.43) when 30% of patients are persistent users and it grows quickly from there. t.co/r0QXhXLvk0