Asian-White disparities in obstetric anal sphincter injury: a systematic review and meta-analysis

Abstract

ObjectiveObstetric anal sphincter injury (OASI) describes severe injury to the perineum and perianal muscles following birth. OASI occurs in approximately 4.4% of vaginal births in the United States (US) however, racial and ethnic inequities in the incidence of OASI have been shown in several high-income countries. Specifically, an increased risk of OASI in individuals who identify as Asian vs. those who identify as white has been documented among residents of the US, Australia, Canada, Western Europe, and the Scandinavian countries. The high rates of OASI among the Asian diaspora in these countries is higher than OASI rates reported among Asian populations residing in Asia. We conducted a systematic review and meta-analysis of studies in high-income, non-Asian countries to further evaluate this relationship. Data Sources, Study eligibility criteria and Study appraisal and synthesis methodsWe searched MEDLINE, OVID, Embase, Emcare, and Cochrane databases from inception to March 2023 for original research studies. Two reviewers followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and Meta-analysis of Observational Studies (MOOSE) recommendations. Meta-analysis was performed using RevMan 5.4 for dichotomous data using the random effects model and the odds ratios (ORs) as effect measures with 95% confidence intervals (CIs). Subgroup analysis was performed among Asian subgroups. Risk of bias was assessed using The Joanna Briggs Institute Critical Appraisal tools. Meta-regression was used to determine sources of between-study heterogeneity. Results & ConclusionTwenty-seven studies conducted in seven countries met inclusion criteria encompassing over 2,337,803 individuals. The pooled incidence of OASI was higher among Asian versus white individuals (pooled OR 1.64, 95% CI 1.48–1.80). Subgroup analyses showed OASI rates were highest among South Asians and among population-based vs. hospital-based studies. Meta-regression showed that moderate heterogeneity remained even after accounting for differences in studies by types of Asian subgroups included, study year, mode of delivery included, and study setting. Qualitative and quantitative research to elucidate underlying causal mechanisms responsible for this relationship is warranted.