Mortality in patients with primary Sjögren's syndrome: a systematic review and meta-analysis

It remains debated whether patients with primary Sjögren's syndrome (pSS) are at greater risk of mortality. We aimed to determine the magnitude of all-cause mortality risk in patients with pSS compared with the general population through a systematic review and meta-analysis.

We searched PubMed, EMBASE and Cochrane Library for studies published from inception to October 2020. Stata meta-analysis software was used to calculate the pooled risk estimates for mortality (standardized mortality ratio, SMR).

Our search identified 2796 articles, of which 14 studies with 14 584 patients were eventually included for the analysis. A total of 902 deaths were observed. Overall, we found a 1.46-fold increased risk of death in pSS patients when compared with the general population [meta-standardized mortality ratio (SMR): 1.46, 95% CI: 1.10, 1.93]. Subgroup analyses showed that mortality risks were higher in European countries (meta-SMR: 1.55, 95% CI: 1.04, 2.33), in retrospective studies (meta-SMR: 1.50, 95% CI: 1.09, 2.05), in studies based on referral cohorts (meta-SMR: 1.55, 95% CI: 1.04, 2.30), in studies that enrolled >500 patients (meta-SMR: 1.70, 95% CI: 1.11, 2.61) and in studies with follow-up time longer than 8 years (meta-SMR: 1.55, 95% CI: 0.87, 2.77). Significantly greater mortality risk was found in patients with older age, male gender, vasculitis, interstitial lung disease, low complements, positive anti-La/SSB and cryoglobulinaemia.

The existing data indicated ∼50% increase of mortality among patients with pSS compared with the general population. More attention should be paid to those patients with poor prognostic factors.