Analysis of clinical features and 7-year all-cause mortality in older male patients with non-thyroidal illness syndrome on general wards

Abstract

Purpose: Older patients with non-thyroidal illness syndrome (NTIS) have a poor prognosis. However, there are few studies on the association of NTIS and mortality among older inpatients on general wards. In a 7-year retrospective observational study, we aimed to investigate the clinical features of NTIS and the association of NTIS and all-cause mortality in older inpatients. Methods: A total of 959 older male inpatients whose average age was 86.3 ± 8.1 years were enrolled and divided into the NTIS group and non-NTIS group. Cox models were performed to explore the association of thyroid hormone level and mortality. Results: Patients had more respiratory disease and chronic kidney disease in the NTIS than in the non-NTIS group, especially in primary nursing care, respiratory failure and haemodialysis patients; serum total protein, albumin, prealbumin, haemoglobin, uric acid and high-density lipoprotein cholesterol levels were lower, and urea nitrogen and fasting blood glucose levels were higher, in the NTIS than in the non-NTIS group. Patients in the NTIS group had a lower survival rate over 7 years follow-up (P < 0.01). A lower free T3 level was associated with all-cause mortality with a HR of 1.50 (1.36, 1.66). Lower free T4 level was associated with reduced all-cause mortality with a HR of 0.91 (0.88, 0.94) even after adjusting for confounding factors (P < 0.01). Conclusions: Among older male inpatients, the survival rate was lower in the NTIS group. A reduced free T3 level with low albumin and Hb levels was associated with all-cause mortality; moreover, a higher free T4 in the normal range may be a strong predictor for long-term mortality risk in hospitalised older male patients.