Correspondence on ‘Impact of rheumatoid arthritis on major cardiovascular events in patients with and without coronary artery disease’
Authors: Gwo-Ping Jong, Lung-Fa Pan, Tsung-Kun Lin, Hung-Yi Chen
Journal: Annals of the Rheumatic Diseases (2020)

Correspondence on 'Impact of rheumatoid arthritis on major cardiovascular events in patients with and without coronary artery disease' Globally, coronary artery disease (CAD) is one of the leading causes of mortality in patients with rheumatoid arthritis (RA). 1 2 The major pathological changes in RA-associated CAD are high rate of unstable coronary plaque and increased local inflammation, as inferred from autopsy reports. 3ecently, Løgstrup et al 4 reported that RA was significantly associated with a 10-year risk of myocardial infarction, major adverse cardiovascular events and all-cause mortality regardless of the presence of CAD in patients undergoing coronary angiography (CAG).While the patients with RA associated CAD carry the largest risk, the additive risk of RA in patients without CAD is minor.These findings were published in the September 2020 issue of the Annals of the Rheumatic Diseases.Certainly, the findings of Løgstrup et al hold significance for clinicians; however, four points remain unaddressed, and we wish to communicate these to the authors.6][7] In recent reports, it has been stated that emphasising the importance of optimal LDL-C control early in life at a younger age. 8However, the LDL level was not described in the baseline characteristics of these four groups.Therefore, the conclusions may not be rigorous without considering these vital factors.Second, several previous clinical trials in patients with CAD have demonstrated that high-intensity statin therapy significantly reduces cardiovascular events when compared with moderate-intensity statin therapy. 9-12Furthermore, it has been established that higher-dose statin therapy was associated with a lower risk for cardiovascular events than moderate-dose statin therapy in patients with CAD. 13 However, the percentages of patients using statin were not comparable and the type and dosage of statin were not described in the baseline characteristics of these four groups.These issues might have nullified some of the results related to this study.Third, despite the higher risk for cardiovascular events, treatment compliance was poor in patients with RA because these patients are given many oral drugs. 14In this situation, the comparison between those with and without CAD among the patients with RA may be influenced by treatment compliance.In particular, there was a low rate of compliance in long-term (over 10 years) follow-up.Thus, treatment compliance rates for patients with RA were probably suboptimal in this study and hence may act as a confounding variable.Finally, during the baseline participation in this study, only patients undergoing CAG were recruited, and the decision was made by the physician to either perform CAG or not.Propensity score matching (PSM) may be suggested to form comparable groups with a priori risk for cardiovascular events and to magnify hidden confounding variables. 15 It is not known what motivates the clinician to ask any given RA patient to undergo CAG.Thus, it is not possible to eliminate the bias introduced by the physician's decision.