Thyroid Function Test Derangements and Mortality in Dialysis Patients: A Systematic Review and Meta-analysis

Background We evaluated current evidence associating thyroid function test result derangements with risk for mortality in patients with chronic kidney failure treated by long-term dialysis. Study Design Systematic review and meta-analysis of cohort studies. Setting & Population Dialysis patients. Selection Criteria for Studies We searched PubMed, Web of Science, Science Citation Index, Cochrane Library, and Embase databases from inception through December 2015. Predictors Hypothyroidism (thyrotropin level greater than reference range) and low triiodothyronine (T3) and thyroxine (T4) levels. Outcomes All-cause and cardiovascular mortality. Results 12 studies involving 14,766 participants (4,450 deaths) were identified. Of those, 6 studies provided data for cardiovascular mortality (2,772 participants with 327 cardiovascular deaths). Overall, confidence in the available evidence was moderate. Pooled adjusted HRs for all-cause mortality associated with hypothyroidism, low T3 level, and low T4 level were 1.24 (95% CI, 1.14-1.34), 1.67 (95% CI, 1.23-2.27), and 2.40 (95% CI, 1.47-3.93), respectively. Pooled adjusted HRs for cardiovascular mortality associated with low T3 and T4 levels were 1.84 (95% CI, 1.24-2.74) and 3.06 (95% CI, 1.29-7.24), respectively. Limitations Fewer studies reporting on T4 and thyrotropin outcomes. Conclusions In patients treated with long-term dialysis, (cardiovascular) mortality is consistently higher in the presence of thyroid function test result derangements. We evaluated current evidence associating thyroid function test result derangements with risk for mortality in patients with chronic kidney failure treated by long-term dialysis. Systematic review and meta-analysis of cohort studies. Dialysis patients. We searched PubMed, Web of Science, Science Citation Index, Cochrane Library, and Embase databases from inception through December 2015. Hypothyroidism (thyrotropin level greater than reference range) and low triiodothyronine (T3) and thyroxine (T4) levels. All-cause and cardiovascular mortality. 12 studies involving 14,766 participants (4,450 deaths) were identified. Of those, 6 studies provided data for cardiovascular mortality (2,772 participants with 327 cardiovascular deaths). Overall, confidence in the available evidence was moderate. Pooled adjusted HRs for all-cause mortality associated with hypothyroidism, low T3 level, and low T4 level were 1.24 (95% CI, 1.14-1.34), 1.67 (95% CI, 1.23-2.27), and 2.40 (95% CI, 1.47-3.93), respectively. Pooled adjusted HRs for cardiovascular mortality associated with low T3 and T4 levels were 1.84 (95% CI, 1.24-2.74) and 3.06 (95% CI, 1.29-7.24), respectively. Fewer studies reporting on T4 and thyrotropin outcomes. In patients treated with long-term dialysis, (cardiovascular) mortality is consistently higher in the presence of thyroid function test result derangements.