Prevalence of and risk factors for hypothyroidism after hemithyroidectomy: a systematic review and meta-analysis

Purpose This systematic review and meta-analysis evaluated the prevalence of and risk factors for hypothyroidism following hemithyroidectomy as new evidence obtained in recent years warranted an update of previous meta-analyses. Methods The PubMed, Embase, and Cochrane Library databases were searched through November 1, 2019, for articles examining the hypothyroidism prevalence and risk factors after lobectomy. The prevalence rate, risk ratio (RR), weighted mean difference (WMD) and standardized mean difference (SMD) were assessed by conducting a meta-analysis of proportions, binary variables, and continuous variables, respectively, using random-effects models. Results Fifty-one studies showed a pooled risk of 29.9% (95% confidence interval (CI), 24.6-35.2%) for hypothyroidism following hemithyroidectomy. Risk factors for the development of postoperative hypothyroidism included the female sex (RR, 1.169; 95% CI, 1.040-1.314;P = 0.009), a higher preoperative thyrotropin (TSH) level (RR, 2.955; 95% CI, 2.399-3.640;P = 0.000), a lower preoperative FT4 level (SMD, -0.818; 95% CI, -1.623--0.013;P = 0.047), concomitant lymphocyte infiltration (RR, 1.558; 95% CI, 1.203-2.018;P = 0.001), Hashimoto's thyroiditis (HT) (RR, 1.480; 95% CI, 1.192-1.838;P = 0.000), a lighter weight of the remaining gland (WMD, -2.740; 95% CI, -3.708--1.772;P = 0.000), and a right side lobectomy (RR, 1.404; 95% CI, 1.075-1.835;P = 0.013). Conclusions Hypothyroidism is a significant complication after lobectomy, and appropriate and personalized surgical strategies should be designed after a careful preoperative assessment based on the estimated risk of hypothyroidism and risk factors.