Statins Use and Risk of Cataracts

We read with great interest the article entitled “Prevention of cataracts by statins: a meta-analysis” by Kostis and Dobrzynski. ¹ The authors analyzed 14 studies including both randomized and observational data and observed a significant decreased risk of cataracts with statins use. Briefly, the authors concluded that “this meta-analysis indicates a clinically relevant protective effect in preventing cataracts (…), it includes all published reports on the topic and that the effect is consistent when analyzed from various aspects.” However, we would like to reflect on some limitations that may impact on the results presented by the authors.

We acknowledge that systematic reviews and meta-analyses have become more widely accepted as a useful tool to critically assess the totality of evidence in a research question. When performed well and reported transparently, incorporating explicit and detailed methods and results, they produce information that can have undoubtedly major impact on medical practice.^2,3 In recent years, there has been accumulating evidence concerning the association of statins with incident cataracts. Randomized clinical trials have not identified an association between statins and cataracts, on the contrary, observational studies have reported conflicting associations between statin use and incident cataracts. ⁴ Apparently, these inconsistent findings in prior studies were the rationale for the question being addressed by Kostis and Dobrzynsk. ¹ However, neither previously published study showing an increased risk of cataracts associated with statins was identified nor included in their meta-analysis.^5–9 In fact, we believe the inclusion of some of the studies in the meta-analysis seems to be somewhat arbitrary and may raise questions about the interpretability and validity of the results. For example, a study that found an association between cataracts and statins in patients with type 2 diabetes ⁵ was cited by the authors in the justification of the meta-analysis but it was not considered for inclusion. The authors included a cohort study that examined the risk of cataract in low-persistence statin users versus high-persistence statin users. ¹⁰ This “all statin users” study was analyzed along with studies in which the comparator was placebo or nonusers of statins. On the other hand, the authors considered eligible the “protective” study by Collins and Altman, ¹¹ a cohort study using general practice databases designed to evaluate the performance of the QStatin scores for predicting the 5-year risk of developing acute renal failure, cataracts, liver dysfunction, and myopathy in 2 million patients receiving statins (including 25 692 incident cataract cases). Because of its sample size, the study by Collins and Altman ¹¹ was the greatest contributor to the pooled effect size for the decreased risk of cataracts with statins in the meta-analysis. ¹ Conversely, a large cohort study by Hippisley-Cox and Coupland ⁵ which found a 16% to 56% increased risk of cataract associated with statins (including 36 541 incident cataract cases in 2 million patients) was not explicitly considered by the authors in their analyses. In our opinion, the authors should clarify this fact. Additionally, more recently large cohort studies that have also found an increased risk of cataracts associated with statins are eligible for further consideration in future analyses.^8,9 If included, this evidence would challenge the overall conclusions and interpretations by Kostis and Dobrzynski. Finally, since much epidemiological evidence already existent was not considered and critically assessed in the published meta-analysis, ¹ we certainly believe these findings cannot be taken as a reason to guide the clinical decision of statin therapy. In fact, firm conclusions about the potential protective effect of statins use in preventing cataracts are still far off, and further research is needed to validate and replicate these findings.