Between-country variation in the utilization of antihypertensive agents: Guidelines and clinical practice.

Variation in antihypertensive drug utilization and guideline preferences between six European countries (Denmark, Finland, Germany, Norway, Sweden, the Netherlands) was investigated. Our objectives were to compare between-country variability in utilization per class of antihypertensive agents and to assess guideline preferences in relation to actual use. Antihypertensive consumption data (2003) was retrieved. We classified antihypertensive agents using ATC-codes: C02CA - alpha-blockers (AB), C03A - thiazide diuretics (TD), C07AB - beta-blockers (BB), C08CA - dihydropyridine calcium antagonists (CA), C09A/C09BA/C09BB - ACE-inhibitors+combinations (AI) and C09C/C09D - angiotensin II receptor blockers+combinations (AT2). For each class, DDDs/1000 persons/day and share (%) of total antihypertensive utilization was calculated. Per class, relative standard deviations (RSD) across countries were computed. Current hypertension guidelines were requested from national medical associations. Total antihypertensive utilization varied considerably, ranging from 152.4 (Netherlands) to 246.9 (Germany) DDDs/1000 persons/day. RSD was highest for TD (106.2%) and AB (93.6%). Where guidelines advocated TDs (Norway and Netherlands), TD utilization was below (Norway) or just above (Netherlands) median TD use. Guidelines recommended TD (Norway and Netherlands), TD/BB/AI (Finland, German Physicians Association) or TD/BB/CA/AI/AT2 (Denmark, German Hypertension Society), Sweden had no recent national guideline. In conclusion, antihypertensive utilization patterns varied largely across these six countries, in absolute and relative terms. Furthermore, guidelines seem disconnected from clinical practice in some countries, and none of the guidelines discuss current utilization. Whether this reflects a need for change in prescribing or re-evaluation of guidelines warrants further research.