Cardiovascular Risk with Non-Steroidal Anti-Inflammatory Drugs: Systematic Review of Population-Based Controlled Observational Studies

David Henry and colleagues reevaluate the evidence from observational studies on the cardiovascular risk associated with non-steroidal anti-inflammatory drugs. Background: Randomised trials have highlighted the cardiovascular risks of non-steroidal anti-inflammatory drugs (NSAIDs) in high doses and sometimes atypical settings. Here, we provide estimates of the comparative risks with individual NSAIDs at typical doses in community settings. Methods and Findings: We performed a systematic review of community-based controlled observational studies. We conducted comprehensive literature searches, extracted adjusted relative risk (RR) estimates, and pooled the estimates for major cardiovascular events associated with use of individual NSAIDs, in different doses, and in populations with low and high background risks of cardiovascular events. We also compared individual drugs in pair-wise (within study) analyses, generating ratios of RRs (RRRs). Thirty case-control studies included 184,946 cardiovascular events, and 21 cohort studies described outcomes in >2.7 million exposed individuals. Of the extensively studied drugs (ten or more studies), the highest overall risks were seen with rofecoxib, 1.45 (95% CI 1.33, 1.59), and diclofenac, 1.40 (1.27, 1.55), and the lowest with ibuprofen, 1.18 (1.11, 1.25), and naproxen, 1.09 (1.02, 1.16). In a sub-set of studies, risk was elevated with low doses of rofecoxib, 1.37 (1.20, 1.57), celecoxib, 1.26 (1.09, 1.47), and diclofenac, 1.22 (1.12, 1.33), and rose in each case with higher doses. Ibuprofen risk was seen only with higher doses. Naproxen was risk-neutral at all doses. Of the less studied drugs etoricoxib, 2.05 (1.45, 2.88), etodolac, 1.55 (1.28, 1.87), and indomethacin, 1.30 (1.19, 1.41), had the highest risks. In pair-wise comparisons, etoricoxib had a higher RR than ibuprofen, RRR = 1.68 (99% CI 1.14, 2.49), and naproxen, RRR = 1.75 (1.16, 2.64); etodolac was not significantly different from naproxen and ibuprofen. Naproxen had a significantly lower risk than ibuprofen, RRR = 0.92 (0.87, 0.99). RR estimates were constant with different background risks for cardiovascular disease and rose early in the course of treatment. Conclusions: This review suggests that among widely used NSAIDs, naproxen and low-dose ibuprofen are least likely to increase cardiovascular risk. Diclofenac in doses available without prescription elevates risk. The data for etoricoxib were sparse, but in pair-wise comparisons this drug had a significantly higher RR than naproxen or ibuprofen. Indomethacin is an older, rather toxic drug, and the evidence on cardiovascular risk casts doubt on its continued clinical use. : Please see later in the article for the Editors' Summary Background: The analgesic (pain relieving), anti-pyretic (fever reducing), and anti-inflammatory (inflammation reducing) properties of the class of drug called non-steroidal anti-inflammatory drugs (NSAIDs)—so called to distinguish this class of drug from steroids, which have similar but additional effects—make NSAIDs one of the most frequently used drugs for the symptomatic treatment of many common conditions. Some preparations of NSAIDs can be bought over the counter, and all are available on prescription, but this class of drug has well documented side effects and risks: people taking NSAIDs are on average four times more likely to develop gastrointestinal complications than people not taking these drugs (that is, the relative risk of gastrointestinal complications is 4), and the relative risk for associated cardiovascular complications—cardiovascular events during treatment with NSAIDs has been one of the most studied adverse drug reactions in history—ranges from 1.0 to 2.0. Why Was This Study Done?: Several large systematic reviews, including one conducted by these researchers, have previously highlighted apparent differences in cardiovascular risk between individual drugs, but these reviews have provided limited information on dose effects and relevant patient characteristics and have not directly compared the cardiovascular risks of each drug. Furthermore, most of these analyses extensively investigated only a few drugs, with little information on some widely available compounds, such as etoricoxib, etodolac, meloxicam, indomethacin, and piroxicam. Therefore, the researchers conducted this study to update cardiovascular risk estimates for all currently available NSAIDs and to compare the risks between individual drugs. In order to investigate the likely effects of over-the-counter use of NSAIDS, the researchers also wanted to include in their review an analysis of the cardiovascular risk at low doses of relevant drugs, over short time periods, and in low risk populations. What Did the Researchers Do and Find?: The researchers included only controlled observational studies in their literature search and review (conducted by searching a wide range of databases for studies published from 1985 until November 2010) because randomized controlled trials have reported only small numbers of cardiovascular events that are insufficient for the purposes of this study. The researchers assessed the methodological quality of selected studies, analyzed adjustment variables (for example, age, sex, other medications), and summarized overall results for individual drugs across studies as pooled relative risk estimates. For the subsets of studies that provided relevant data, they pooled within-study relative risk estimates with high and low doses and in people at high and low risk of cardiovascular events, and performed a series of within-study (pair-wise) comparisons and for each pair of drugs, to estimate their comparative relative risks by using a validated online tool to give a ratio of relative risks. What Do These Findings Mean?: This updated systematic review gives some new information on some familiar NSAIDs, and provides potentially important information on some little studied ones, which will help to inform clinical and regulatory decisions. The specific findings suggest that among widely used NSAIDs, naproxen and low-dose ibuprofen are least likely to increase cardiovascular risk, whereas diclofenac in doses available without prescription elevates risk. Based on sparse data, etoricoxib has a high risk of cardiovascular events and is similar to drugs that have been withdrawn because of safety concerns. Indomethacin is an older, rather toxic drug, and the new evidence on cardiovascular risk casts doubt on its continued clinical use. Additional Information: Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001098.