Cardiovascular and Cerebrovascular Events After Parathyroidectomy in Patients on Renal Replacement Therapy.

BACKGROUND: A majority of patients with end-stage renal disease suffer from secondary hyperparathyroidism, which is associated with osteoporosis and cardiovascular disease. Parathyroidectomy (PTX) is often necessary despite medical treatment. However, the effect of PTX on cardio- and cerebrovascular events (CVE) remains unclear. Data on the effect of PTX from population-based studies are scarce. Some studies have shown decreased incidence of CVE after PTX. The aim of this study was to evaluate the effect of PTX on risk of CVE in patients on renal replacement therapy. METHODS: We performed a nested case-control study within the Swedish Renal Registry (SRR) by matching PTX patients on dialysis or with functioning renal allograft with up to five non-PTX controls for age, sex and underlying renal disease. To calculate time to CVE, i.e., myocardial infarct, stroke and transient ischemic attack, control patients were assigned the calendar date (d) of the PTX of the case patient. Crude and adjusted proportional hazards regressions with random effect (frailty) were used to calculate hazard ratios for CVE. RESULTS: The study cohort included 20,056 patients in the SRR between 1991 and 2009. Among these, 579 patients had undergone PTX, 423 during dialysis and 156 during time with functioning renal allograft. These patients were matched with 1234 dialysis and 736 transplanted non-PTX patients. The adjusted hazard ratio (HR) with 95% confidence interval (CI) of CVE after PTX was 1.24 (1.03-1.49) for dialysis patients compared with non-PTX patients. Corresponding results for patients with renal allograft at d were HR (95% CI) 0.53 (0.34-0.84). CONCLUSIONS: PTX patients on dialysis at d had a higher risk of CVE than patients without PTX. Patients with renal allograft at d on the other had a lower risk after PTX than patients without PTX.

Total versus subtotal parathyroidectomy for secondary hyperparathyroidism.

BACKGROUND: It remains unclear whether total or subtotal parathyroidectomy for secondary hyperparathyroidism yields the best outcomes. We investigated mortality, cardiovascular events, hip fracture, and recurrent parathyroidectomy after total versus subtotal parathyroidectomy in patients on renal replacement therapy. METHODS: Using the Swedish Renal Registry, the surgical registry for thyroid and parathyroid surgery, and the National Inpatient Registry, we identified patients who underwent parathyroidectomy between 1991 and 2013. We calculated the risk of outcome after total versus subtotal parathyroidectomy using COX's regression, adjusting for age, sex, cause of renal disease, time with a functioning graft before and after parathyroidectomy, Charlson comorbidity index, year of surgery, prevalent cardiovascular disease, time on dialysis, renal transplantation at parathyroidectomy, and treatment with calcimimetics before parathyroidectomy. RESULTS: There were 824 patients who underwent parathyroidectomy, 388 total and 436 subtotal. There was no difference in mortality or risk of incident hip fracture between groups. Comparing the subtotal with the total parathyroidectomy, the adjusted hazard ratio (95% confidence interval) for cardiovascular events was 0.43 (0.25-0.72) and for recurrent parathyroidectomy 3.33 (1.33-8.32). CONCLUSION: There was a higher risk of cardiovascular events in patients after total parathyroidectomy compared with subtotal parathyroidectomy, but a lower risk of recurrent parathyroidectomy.

The Effect of Parathyroidectomy on Risk of Hip Fracture in Secondary Hyperparathyroidism.

BACKGROUND: Secondary hyperparathyroidism increases the risk for fractures. Despite improvement in medical therapy, surgical parathyroidectomy (PTX) often becomes necessary, but its effect on risk of fractures is not clear. Our aim was to study the effect of parathyroidectomy on the risk of hip fractures in patients on dialysis or with a functioning renal graft at time of parathyroidectomy. DESIGN: In a cohort of 20,056 patients on dialysis or with functioning renal allograft, we identified 590 patients who underwent parathyroidectomy between 1991 and 2009. Of these, 579 were matched with 1970 non-PTX patients on age, sex, cause of renal disease and functioning renal allograft or not at the time of PTX or at the corresponding time for non-PTX patients (t). We calculated the risk for hip fracture after PTX using crude and adjusted Cox proportional hazards regressions, adjusting for time in renal replacement therapy before t, time with functioning renal allograft before and after t, comorbidity at t and a hip fracture before t. RESULTS: The adjusted hazard ratio (95% confidence interval) for hip fracture was 0.40 (0.18-0.88) for PTX patients, compared to non-PTX patients. When analyses were performed separately for sex, only women had a lower risk of hip fracture after PTX compared to non-PTX patients. The risk of hip fracture after PTX was similar in patients with or without functioning renal allograft at time for PTX. CONCLUSION: Parathyroidectomy is associated with a lower risk of hip fracture in female patients with secondary hyperparathyroidism.

The effect of parathyroidectomy on patient survival in secondary hyperparathyroidism.

BACKGROUND: Secondary hyperparathyroidism is a common condition in patients with end-stage renal disease and is associated with osteoporosis and cardiovascular disease. Despite improved medical treatment, parathyroidectomy (PTX) is still necessary for many patients on renal replacement therapy. The aim of this study was to evaluate the effect of PTX on patient survival. METHODS: A nested index-referent study was performed within the Swedish Renal Registry (SRR). Patients on maintenance dialysis and transplantation at the time of PTX were analysed separately. The PTX patients in each of these strata were matched for age, sex and underlying renal diseases with up to five referent patients who had not undergone PTX. To calculate survival time and hazard ratios, indexes and referents were assigned the calendar date (d) of the PTX of the index patient. The risk of death after PTX was calculated using crude and adjusted Cox proportional hazards regressions. RESULTS: There were 20 056 patients in the SRR between 1991 and 2009. Of these, 579 (423 on dialysis and 156 with a renal transplant at d) incident patients with PTX were matched with 1234/892 non-PTX patients. The adjusted relative risk of death was a hazard ratio (HR) of 0.80 [95% confidence interval (CI) 0.65-0.99] for dialysis patients at d who had undergone PTX compared with matched patients who had not. Corresponding results for the patients with a renal allograft at d were an HR of 1.10 (95% CI 0.71-1.70). CONCLUSIONS: PTX was associated with improved survival in patients on maintenance dialysis but not in patients with renal allograft.

Temporal trends and risk factors for parathyroidectomy in the Swedish dialysis and transplant population - a nationwide, population-based study 1991 - 2009.

BACKGROUND: Many patients on renal replacement therapy (RRT) require parathyroidectomy (PTX). Trends and current rates of PTX on a national level are not known. Furthermore, it is not completely clear which factors influence rates of PTX. Thus, our aim was to investigate the incidence, regional distribution and factors associated with PTX as well as possible temporal changes, in the Swedish RRT population. METHODS: From the Swedish Renal Registry we extracted data on 20 015 patients on RRT between 1991 and 2009. In these, 679 incident PTX (3.4%) were identified by linkage with the National Inpatient Registry, and the Scandinavian Quality Registry for Thyroid Parathyroid and Adrenal Surgery. Poisson models were used to estimate rates per calendar year, adjusted for risk factors such as gender, age, time with renal transplant, and underlying cause of renal disease. RESULTS: The PTX rate was 8.8/1 000 person-years. There was a significant increase 2001-2004 after which the rate fell, as compared with year 2000. Female gender, non-diabetic cause of renal disease and age between 40-55 were all associated with an increased frequency of PTX. CONCLUSION: The rise in PTX rates after year 2000 might reflect increasing awareness of the potential benefits of PTX. The introduction of calcimimetics and paricalcitol might explain the decreased rate after 2005.

Impact of parathyroid hormone on bone density in long-term renal transplant patients with good graft function.

BACKGROUND: It remains unknown whether low-grade hyperparathyroidism persisting beyond the first year postrenal transplantation has any impact on bone density. METHODS: Parathyroid hormone (PTH), glomerular filtration rate (GFR), and bone density (by dual-energy x-ray absorptiometry [DXA]) were monitored in the follow-up of our transplant patients. Of 260 long-term renal transplant patients, 41 fulfilled the following criteria: Two DXA measurements performed at least five years apart (median 6.8 years, range 5-9); GFR>or=35 ml/min per 1.73 m body surface area (median 50, range 35-76); no bisphosphonate treatment or parathyroidectomy in the study period. RESULTS: In all, 40% had mean PTH values above the normal limit 6.9 pmol/L (65 pg/ml), and the range was 0.9-17 pmol/L. In the first DXA, 8 of 41 patients had osteoporosis and 17 more had osteopenia. Hip bone density Z-score was -0.60 SD, range (-2.6 to +2.3). The absolute median value (g/cm) remained unchanged until the second DXA, but among patients there was a variation which ranged from -2.3% to +1.7% per year. In a simple linear regression analysis, these changes were significantly correlated to mean PTH (r=0.16, P=0.010). Median lumbar spine bone density was also reduced in the first DXA and was not different at follow-up, but with this variable individual changes did not correlate to mean PTH. CONCLUSION: Bone density is often reduced and PTH remains elevated in long-term renal transplant patients with good transplant function. Slight to moderate elevation of PTH is associated with reduction in hip bone mineral density.