Inclusion of the birth cohort dimension improved description and explanation of trends in statin use.
OBJECTIVE
Including the birth cohort dimension improves trend studies of mortality and health. We investigated the effect of including the birth cohort dimension in trend studies of prescription drug use by studying prevalence of statin use among adults.


METHODS
Data from a drug prescription database in the Netherlands (IADB.nl) were used to obtain the number of users of statin per 1,000 population (prevalence) in the age range 18-85 years from 1994 to 2008. We applied descriptive graphs and standard age-period-cohort (APC) models.


RESULTS
From 1994 to 2008, the prevalence increased from ∼10 to ∼90 users per 1,000 population, with the peak in prevalence shifting from age 63 to 78 years. The APC model shows patterns that were masked in the age-period (AP) model. The prevalence rate ratio increased from the 1911 birth cohort to the 1930 birth cohort and then declined. Similar for both sexes, adding nonlinear period effects contributed ∼4.4% to reductions in deviance, whereas adding nonlinear birth cohort effects contributed ∼12.9%.


CONCLUSIONS
Adding the birth cohort dimension to AP analysis is valuable for academic and professional practice as trends can be more accurately described and explained and it can help improve projections of future trends.
Unit PharmacoEpidemiology & PharmacoEconomics (PE(2)), Department of Pharmacy, University of Groningen, A. Deusinglaan 1, Groningen 9713 AV, The Netherlands. maarten.bijlsma@rug.nl
Maarten J
MJ
Bijlsma
Eelko
E
Hak
Jens H J
JH
Bos
Lolkje T W
LT
de Jong-van den Berg
Fanny
F
Janssen
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004363:Drug Utilization / Q000706:statistics & numerical data / Q000639:trends*; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D016013:Likelihood Functions; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D017891:Pharmacoepidemiology / Q000379:methods* / Q000706:statistics & numerical data; D015995:Prevalence; D017678:Sex Distribution
D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors