Cui bono? Or: context matters.

by Andreas Baumann

The non-steroidal anti-inflammatory drug (NSAID) diclofenac has come under some flak recently, since a recent paper showed that it has a risk profile similar to the NSAID rofecoxib (brand name Vioxx), which was withdrawn from circulation for this reason exactly.

NSAIDs function by inhibiting two enzymes, COX-1 and COX-2. Inhibition of COX-1 is typically correlated with stomach complaints, and for this reason, research into selective COX-2 inhibitors have been conducted. However, research findings such as the ones revealed in the paper referenced seem to indicate that selective COX-2 inhibitors is related to increased risk of cardiovascular events. For this reason, the authors recommend that doctors should prescribe non-selective COX inhibitors, and that countries should consider banning diclofenac.

The problem with the paper referenced is that it fails to consider differential applications of NSAIDS. The two major user groups of these drugs are people engaging in sports (and suffering related injuries) and people suffering from arthritis.

Many studies – including the meta-analysis in the paper referenced above – indicate an increased risk of ca. 40% of cardiovascular events when using selective COX inhibitors. For this reason, the authors recommend banning drugs such as diclofenac.

However, while I applaud the authors’ commitment to revealing this increased risk, it is only a problem for one of the user groups, namely, the arthritis sufferers, where increased cardiovascular risk is very prevalent. For the user group consisting of athletes and athletic people – a group with very low levels of cardiovascular risk – the impact of a 40% increase in cardiovascular risk is very low. On the other hand, the adverse effects relating to stomach complaints affects this group as well, and banning selective inhibitors would therefore lead this group to suffer increased adverse effects without a practically significant reduction in risk.

Summa summarum: the adverse effects of drugs cannot be evaluated without considering differential impacts on different user groups. For this reason, the selection of non-selective COX inhibitors for the elderly and selective inhibitors for otherwise healthy people with low cardiovascular risk is – in my opinion – better administered in the dispensation part of the system instead of the regulation part. Physicians can – and should – make contextual decisions which perform better than catch-all decisions in terms of individual welfare.