Aims: This study aimed to assess all-cause and cause-specific standardized mortality ratios (SMRs) in patients with systemic lupus erythematosus (SLE). Methods: We surveyed studies examining all-cause and/or cause-specific SMR in patients with SLE compared to the general population using PUBMED, EMBASE and Cochrane databases and manual searches. We performed a meta-analysis of all-cause, sex-specific, ethnicity-specific, and cause-specific SMRs in SLE patients. Results: Fifteen reports including 26,101 patients with SLE with 4640 deaths met the inclusion criteria. Compared to the general population, all-cause SMR was significantly increased 2.6-fold in patients with SLE (SMR 2.663, 95% CI 2.090–3.393, p < 1.0 × 10⁻⁸). Stratification by ethnicity showed that all-cause SMR was 2.721 (95% CI 1.867–3.966, p = 1.9 × 10⁻⁶) in Caucasians and 2.587 (95% CI 1.475–4.535, p = 0.001) in Asians. Sex-specific meta-analysis revealed that all-cause SMR was 3.141 (95% CI 2.351–4.198, p < 1.0 × 10⁻⁸) for women and 3.516 (95% CI 2.928–4.221, p < 1.0 × 10⁻⁸) for men. The risk of mortality was significantly increased for mortality due to renal disease (SMR 4.689, 95% CI 2.357–9.330, p = 1.10 × 10⁻⁵), cardiovascular disease (CVD) (SMR 2.253, 95% CI 1.304–3.892, p = 0.004), and infection (SMR 4.980, 95% CI 3.876–6.398, p < 1.0 × 10⁻⁸), although there was no significant increase in SMR for mortality due to cancer (SMR 1.163, 95% CI 0.572–2.363, p = 0.676). Conclusions: Patients with SLE had higher rates of death from all causes, regardless of sex, ethnicity, renal disease, CVD or infection. However, the risk of death due to malignancy was not increased.

The number of medical studies being published is increasing exponentially, and clinicians must routinely process large amounts of new information. Moreover, the results of individual studies are often insufficient to provide confident answers, as their results are not consistently reproducible. A meta-analysis is a statistical method for combining the results of different studies on the same topic and it may resolve conflicts among studies. Meta-analysis is being used increasingly and plays an important role in medical research. This review introduces the basic concepts, steps, advantages, and caveats of meta-analysis, to help clinicians understand it in clinical practice and research. A major advantage of a meta-analysis is that it produces a precise estimate of the effect size, with considerably increased statistical power, which is important when the power of the primary study is limited because of a small sample size. A meta-analysis may yield conclusive results when individual studies are inconclusive. Furthermore, meta-analyses investigate the source of variation and different effects among subgroups. In summary, a meta-analysis is an objective, quantitative method that provides less biased estimates on a specific topic. Understanding how to conduct a meta-analysis aids clinicians in the process of making clinical decisions.

Objective . To assess whether combined evidence shows the association between the protein tyrosine phosphatase non-receptor 22 (PTPN22) C1858T polymorphism and autoimmune diseases, and to summarize the effect size of the polymorphism associated with susceptibility of autoimmune diseases. Methods . We surveyed studies on the PTPN22 C1858T polymorphism and autoimmune diseases using comprehensive Medline search and review of the references. Meta-analysis was performed for genotypes T/T (recessive effect), T/T + C/T (dominant effect) and T-allele in random effects models. Results . Twenty-nine studies with 43 comparisons including 13 rheumatoid arthritis (RA), six systemic lupus erythematosus (SLE), six type-1 DM (T1D), three Grave's disease (GD), four inflammatory bowel diseases (IBD), three juvenile idiopathic arthritis (JIA), two psoriasis, two multiple sclerosis, two Addison's disease and two Celiac disease were available for the meta-analysis. The overall odds ratios (ORS) for T-allele, T/T and T/T + C/T genotypes were significantly increased in RA, SLE, GD and T1D (OR for T-allele = 1.58, 1.49, 1.85, 1.61, respectively, P < 0.00001). This meta-analysis showed the association between the T-allele and the T/T genotype and JIA (OR = 1.34, P = 0.03; OR = 1.97, P = 0.02) but did not reveal the association between the PTPN22 C1858T polymorphism and IBD, psoriasis, multiple sclerosis, Addison's disease and Celiac disease. Conclusion . This meta-analysis demonstrates that the PTPN22 1858T allele confers susceptibility to RA, SLE, GD, T1D and JIA, supporting evidence of association of the PTPN22 gene with subgroup of autoimmune diseases.

Lee YH. Ann Lab Med. 2015 May;35(3):283-287. https://doi.org/10.3343/alm.2015.35.3.283