SURVIVAL AFTER THE DIAGNOSIS OF HYPERPARATHYROIDISM - A POPULATION-BASED STUDY

BACKGROUND: Reports of increased mortality from cardiovascular disease and malignancy in primary hyperparathyroidism have been based primari ly on patients who have undergone parathyroidectomy. In order to asses s the true impact of primary hyperthyroidism on mortality in the gener al population, we assessed survival in a large inception cohort of Roc hester, Minnesota residents with primary hyperparathyroidism initially diagnosed over a 28-year span, the majority of whom were fell-owed wi th uncomplicated disease. METHODS: All Rochester residents with primar y hyperparathyroidism first recognized in 1965 to 1992 were identified through the Rochester Epidemiology project medical records linkage sy stem. Included as cases were patients with pathologic confirmation of hyperthyroidism, hypercalcemia with inappropriately elevated parathyro id hormone levels, or hypercalcemia for more than a year with no other cause. Survival tvas estimated using the Kaplan Meier product-limit m ethod. The Cox proportional hazards model was used to determine associ ations, as relative hazards (RR) with 95% confidence intervals (CI), o f various risk factors with time to death. RESULTS: During the study p eriod, 435 cases of primary hyperparathyroidism were identified. Altog ether, parathyroid surgery was performed on 126 patients (29%), with a mean delay between the initial elevated serum calcium level and surge ry of 3.3 years. Patients who underwent surgery had higher maximum ser um calcium levels than the patients who were observed (mean +/- SD, 11 .3 +/- 0.7 versus 10.7 +/- 0.4 mg/dL, P <0.001), but their mean ages w ere similar (54 +/- 16 versus 56 +/- 17 years). Overall survival in th e patients with primary hyperthyroidism was better than expected (P = 0.02), but by age adjusted multivariate analysis, higher maximal serum calcium level was an independent predictor of mortality (RR = 1.3 per mg/dL; 95% CI: 1.1-1.6; P <0.02). CONCLUSION: Overall survival is not adversely affected among unselected patients with mild primary HPT in the community, although patients with more severe disease, as manifes ted by higher serum calcium levels, may have an increased risk of deat h. (C) 1998 by Excerpta Medica, Inc.