Table 2. Baseline characteristics of the studies included in the meta-analysis.

Reference (first author)	Design of study	Duration of follow-up (months)	Baseline PTH		Type of surgery	Type of control group	Inclusion criteria	Exclusion criteria
			PTX	CTRL
Ivarsson et al. 2015	Cohort-multicenter- prospective	61.3	N/A	N/A	Total and subtotal PTX	Between one and five patients randomly matched who had not undergone PTX. The matching criteria were birth year in 10-year categories, sex and cause of ESKD in categories (autosomal dominant polycystic kidney disease, diabetes mellitus, glomerulonephritis, nephrosclerosis, pyelonephritis and other/unknown.	Patients on maintenance dialysis and transplantation with SHPT	Errors in reporting of patient information censoring on the same day as initiation of RRT
Komaba et al. 2015	Cohort-multicenter- prospective	12	96 (28–236)	669 (570–870)	Total and subtotal PTX	Propensity score-matched patients who had not despite severe SHPT	≥ 18 years of age with SHPT and were receiving haemodialysis thrice weekly for more than 3 months	No data on demographic characteristics, dialysis prescription, intact PTH levels, or history of PTX
Conzo et al. 2013	One-center retrospective	60	142.08 ± 64.01	102.94 ± 32.51	Total PTX and total PTX with auto-transplantation	Patients with indication for PTX but refusing surgery	SHPT, unresponsive to medical treatment iPTH levels > 53–84, 8 pmol/L, serum P level > 2,09 mmol/l, US enlarged parathyroid glands (> 1 cm or >500 mm3) and persisting clinical symptoms, six months after medical therapy	Renal transplantation,
Sharma et al. 2013	Retrospective and matched-cohort study	33.6	N/A	N/A	Near-total parathyroidectomy	For each NTPTX patient, controls were individually matched for age (±2 years), sex, race, diabetes as cause of end-stage renal disease, dialysis duration (vintage), year they started dialysis (±1 year), and dialysis modality	Prevalent haemodialysis or peritoneal dialysis with SHPT	Kidney transplant, no SHPT, no records on dialysis modality
Goldstein et al 2013	Retrospective cohort study	23	1554	1360	Total parathyroidectomy with auto-transplantation	Patients with refractory SHPT not submitted to PTX	PTH greater than 800 pg/ml on calcitriol or in the presence of hyperphosphatemiaand/or hypercalcemia which prevented the use of calcitriol	Kidney transplant and predialysis patients No SHPT
Iwamoto et al 2012	Retrospective cohort study	53	884.5 ± 388.5	199.0 ± 120.2	Total PTX without autotransplantation	Matched patients for sex, age, underlying disease and prior dialysis history	PTH >500 pg/mL and enlarged parathyroid glands confirmed by imaging, enlarged parathyroid gland with imaging and resistant to reduction of iPTH to below 200 pg/mL for hypercalcemia (corrected Ca>11.0 mg/dL) with VDRAs.	N/A
Kestenbaum et al. 2004	prospective cohort study	53.4	N/A	N/A	Total+subtotal PTX	Individually matched by age, race, gender, cause of ESKD, dialysis duration, prior transplantation status, and dialysis modality	at least 18 years old and had initiated renal replacement therapy with SHPT	Death, lost to follow-up, or underwent PTX during the first 90 days of renal replacement therapy
Trombetti et al. 2007	retrospective cohort study	360	N/A	N/A	Subtotal or total PTX with autotransplantation	two matched controls for each PTX case	ESKD and severe hyperparathyroidism	Kidney transplant, no records, no SHPT
Ho LC et al. 2016	retrospective cohort study	41.52±30.12	N/A	N/A	N/A	The parathyroidectomized patients were matched with the controls based on propensity score for parathyroidectomy	Prevalent dialysis with unremitting SHPT	Renal transplantation prior to dialysis or a history of any kind of malignancy before the initiation of long-term dialysis
Moldovan et al. 2015	prospective cohort study	24	2037	1282	Subtotal or total PTX	patients with iPTH over 700 pg/ml, without surgical intervention and treated with specific drugs	severe sHPT, non-responsive to medical treatment with hypercalcemia and hyperphosphatemia	ESKD patients with SHPT and no parathyroid surgery
Li-Wedong et al 2016	prospective cohort study	12	395.3 ± 332.4	349.8 ± 334.5	N/A	Dialysed patient with SHPT	Age>18 years and less than 70 years old. (Duration of HD is more than 3 months. Patients with SHPT (Based on the 2002 KDOQI)	patients with malignant neoplasms, active tuberculosis, AIDS, receiving kidney transplant surgery within one year, pregnancy or lactation, life expectancy being less than 12 months, acute malnutrition, uncontrolled hypertension, severe anemia, serious liver diseases or interrupted follow-up because of all kinds of reasons
Costa-Hong et al 2007	prospective cohort study	N/A	1278 ±699	1243± 753	Total PTX with autotransplantation in the forearm	Patients who had the diagnosis of medically resistant SHPT and not submitted to PTX	Resistance to medical treatment that was defined as serum levels of parathyroid hormone (PTH) and phosphate greater than 800 pg/mL and 6.5 mg/100 mL, respectively, after a minimum of 6 months of treatment.	Renal transplantation, previous myocardial revascularization, smokers, individuals using lipid-lowering drugs, patients with diabetes, and those with a history of heart failure, stroke, unstable angina, or myocardial infarction within 12 months preceding the initiation of the study
Dussol B et al 2007	prospective cohort study	96	N/A	N/A	Total+subtotal PTX	Patients undergoing chronic hemodialysis treatment	N/A	N/A
Ma T-L et al 2015	Prospective cohort study	36	N/A	N/A	N/A	Hemodialysed patients with iPTH values greater than 800 pg/dL	N/A	N/A
Lin H-C 2014	prospective cohort study	72	1011 ±247	1007 ± 251	total PTX with autograft to the brachioradialis muscle in the forearm without arteriovenous shunt.	ESKD patients who were treated with maintenance haemodialysis and who had intact parathyroid hormone (PTH) levels > 800 pg/ml not receiving PTX	Haemodialysis patients with severe secondary hyperparathyroidism. Severe SHPTH was diagnosed when a patient’s PTH level was higher than 800 pg/ml and was associated with the following symptoms: bone and joint pain, muscle weakness, irritability, itching, bone loss, anaemia resistant to erythropoietin, cardiomyopathy or calciphylaxis.	Switched ti peritoneal dialysis Transfer to other hospital Incomplete medical history Received kidney transplant Not eligible for operation Had previous PTX

Abbreviations: PTH-parathormone, RRT-renal replacement therapy, PTX-parathyroidectomy, SHPT- hyperparathyroidism, ESKD- end–stage kidney disease, VDRAs- vitamin D receptor activators, N/A- not available