Knopf H, Melchert HU, Bertelsmann A (2000): Consumption of calcium antagonists: Results of the German National Health Surveys
Pharmacoepidemiol. Drug Safety 9: 221-233.

Purpose - In generating firm conclusions concerning the efficacy and safety of drugs, the description of the exposed population should be one of the first steps in pharmacoepidemiological studies. The present investigation describes the frequency of usage of calcium antagonists in relation to sociodemographic data and parameters of morbidity statistics. Additionally statements are made concerning co-medication, drug tolerability and side-effects. Methods - In four studies conducted between 1985 and 1998 a representative sample (total approximately 19,000 study participants) of the general population aged 25-69 years and resident in the area of the former Federal Republic of Germany (FRG) was interviewed about their total drug use up to 7days before the day of investigation using a standardized questionnaire. Relevant health data, lifestyle and behaviour characteristics as well as data on morbidity and important physiological parameters were collected in all investigations. Results - From 1985 to 1990, the use of calcium channel blockers increased for men from 3.4 to 4.6% and for women from 3.7 to 4.1%. In the last survey (1998) only 2.5% of the male and 3.4% of the female study population were users of this drug group. No statistically significant differences in the usage of calcium channel blockers between males and females were found in any of the surveys. The most frequent indication (42.7%) for the use of calcium antagonists was hypertension. The usage of calcium antagonists with the indication 'hypertension' increased from 21.7% in 1985 to 74.8% in 1998. Considering the whole observational period more than half of all preparations contained nifedipine as the active agent. The percentage of nifedipine-containing drugs consumed decreased from 56.7% in 1985 to 26.7% in 1998. More than 90% of all users of calcium channel blockers assessed the tolerability of this drug group as very good. The average percentage of registered side-effects reached 3.4%, with the highest number of adverse drug reactions for the nifedipine-containing calcium antagonists. More than 90% of all users of calcium antagonists were subject to co-medication of one or more drugs. The most frequently used additional medication belonged to the group of cardiac drugs. Compared to study participants without medication in the past 7 days, users of calcium channel blockers showed significantly higher mean values for serum glucose and systolic blood pressure. Conclusions - Collecting data on drug use as part of health surveys makes it possible to assess the usage of calcium antagonists in relation to relevant health conditions in real daily life situations as presented by the subjects. Although drug utilization surveys of this kind can give essential information concerning real drug usage, their results are subject to some methodological restraints. Statements concerning causal inferences of observed consumption trends are possible only with limitations. For this purpose, methods of analytical epidemiology must be used with a longitudinal study design.