A parallel randomised controlled trial of surgery versus observation in patients 65 year or older with primary hyperparathyroidism

Background A bone density T-score <2 s.d., is an indication for surgery of primary hyperparathyroidism (pHPT). However, the impact of pHPT surgery on bone density in older patients is unclear. Methods Patients 65 > years referred for first time surgery for pHPT were randomised to operation or control. Exclusion criteria were a Z-score < - 2.5 SD and ionised calcium > 1.50 mmol/L. Bone density was evaluated preoperatively and at one and two years. Primary outcome was hip bone density. Secondary outcomes included lumbar spine bone density and renal function. Analysis of change from baseline was performed using a mixed-model repeated-measures ANOVA (MMRMA). Continuous variables were analysed using Satterthwaite's t-test. Results 252 were screened and 102 patients randomised, 50 to observation and 52 to surgery. The mean age was 72 years. 81 patients were available for analysis of the primary outcome. Total hip bone density increased with mean 1.31% in the surgery group (95 per cent confidence interval -0.2 to 2.81%) and decreased with mean -1.38 % in the control group ( -2.59 to -0.17%), p=0.006, MMRMA, p=0.001. Bone density at the lumbar spine increased by 4.56% in the surgery group (3.02 to 6.11%) and in the observation group by 0.17 % (1.12 to 1.45%); p<0.001, MMRMA p=0.001. No difference in renal function between the groups were shown, MMRMA, p= 0.232. Conclusion Patients >65 years with moderate hypercalcaemia increased slightly in bone density after parathyroidectomy. If this will translate into a clinically meaningful reduced fracture risk is an open question.