Long-term frequent use of non-steroidal anti-inflammatory drugs might protect patients with ankylosing spondylitis from cardiovascular diseases: a nationwide case-control study

The objective of this case-control study was to investigate the risk of cardiovascular disease (CVD) following non-steroidal anti-inflammatory drug (NSAID) use in patients with ankylosing spondylitis (AS). A total of 10,763 new AS patients were identified from the National Taiwan Health Insurance claims database during the period from 1997 to 2008. In all, 421 AS patients with CVD were recruited as cases, and up to 2-fold as many sex- and age-matched controls were selected. Logistic regression models were used to estimate the odds ratio (OR) between NSAID use and CVD incidence. The medication possession rate (MPR) was used to evaluate NSAID exposure during the study period. AS patients had increased risk of CVD (OR, 1.68; 95% confidence interval (CI), 1.57 to 1.80). Among frequent (MPR≥80%) COX II users, the risks for all types of CVD were ten times lower than those among non-users at 24 months (OR, 0.08; 95% CI, 0.01 to 0.92). Among frequent NSAID users, the risks of major adverse cardiac event (MACE) were significantly lower at 12 months (OR, 0.23; 95% CI, 0.07 to 0.76)--a trend showing that longer exposure correlated with lower risk. Regarding non-frequent NSAID users (MPR