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Meltzer C, Klau M, Gurushanthaiah D, et al. Surgeon Volume in Parathyroid Surgery—Surgical Efficiency, Outcomes, and Utilization. JAMA Otolaryngol Head Neck Surg. 2017;143(8):843–847. doi:10.1001/jamaoto.2017.0124
Surgery is the standard of care for primary hyperparathyroidism, with US surgeons annually performing an estimated 17 000 parathyroidectomies.1 Although a well-documented association between higher surgeon volume and better outcomes exists for thyroid surgery,2,3 a single study4 examines this relationship for parathyroid surgery. Our goal was to examine the association between surgeon volume and 30-day rates of complications, mortality, and postdischarge utilization among patients undergoing parathyroidectomy. We also assessed surgical efficiency, length of stay, and the proportion of outpatient cases (discharge within 8 hours of surgery).
The study population consisted of 2080 unique adult patients in the Kaiser Permanente Northern California and Southern California regions with a single parathyroid procedure performed by a low- or high-volume surgeon from 2008 to 2013. We identified patients by International Statistical Classification of Diseases (ICD)-9 codes for surgical procedures (06.89, 06.99).
To maximize the likelihood of detecting differences in outcomes, we compared low- and high-volume surgeons, who respectively performed 20 or fewer and more than 40 cases per year.3 We measured 25 complications identified by ICD-9 codes as present or absent during the first 30 postoperative days. We measured 30-day rates of all-cause readmissions and emergency department visits and surgical cut-to-close times and length of stay from arrival in the operating room to discharge.
Patients receiving parathyroid procedures from low- and high-volume surgeons were matched using propensity scores derived from regression modeling of multiple covariates (Table 1). Income and education were imputed from census block–level data; all other data were available through an electronic health record. Patients of low- and high-volume surgeons were matched 1:1 by procedure and propensity score, and covariate balance was assessed by standardized differences in means.5 Differences in outcomes were assessed with t tests for continuous variables and χ2 tests for categorical variables (SAS statistical software, version 9.2; SAS Institute). The Kaiser Permanente Northern California institutional review board approved this study. Informed consent was waived because the study was retrospective and analyzed existing electronic health record data.
Propensity score matching created 547 matched pairs (Table 1). Compared with patients of low-volume surgeons, patients of high-volume surgeons had a lower rate of vocal cord paralysis (absolute difference, −1.4%; 95% CI, −2.5% to −0.4%). The number needed to treat (NNT) to avoid 1 case of vocal cord paralysis was 71; based on the upper bound of the confidence interval, the NNT could be as low as 34. High-volume surgeons performed more outpatient procedures (absolute difference, 25.5%; 95% CI, 19.6 to 31.0). No other differences reached statistical significance (Table 2).
Compared with a previous study on total thyroid procedures, patients of low- and high-volume surgeons had excellent outcomes with no clinically meaningful differences. Outpatient surgery is safe, with increased efficiency and no greater risk of complications. The value of increased efficiency through outpatient thyroid surgery has been documented2; further study is required to assess the value of this efficiency for parathyroid surgery.
Study limitations include the possibility that unmeasured factors affected the findings. A greater difference between cut points for low-volume and high-volume surgeons may have revealed additional significant differences in outcomes. We could not match all patients receiving procedures from high-volume surgeons to patients receiving the same procedures from low-volume surgeons; the size of the matched-pair groups may have precluded detecting associations between surgeon volume and rare events. The generalizability to other settings is unknown.
Study strengths include a robust methodology to attempt to control for multiple sources of bias, the assessment of an extensive list of complications, and the assessment of 30-day parathyroidectomy-specific outcomes and utilization. Our findings led us to undertake a quality improvement initiative in which patients requiring parathyroid surgery are treated by higher-volume surgeons under care pathways we designed to standardize the treatment of patients with primary hyperparathyroidism.
Corresponding Author: Charles Meltzer, MD, The Permanente Medical Group, 401 Bicentennial Wy, Santa Rosa, CA 95403 (email@example.com).
Accepted for Publication: January 9, 2017.
Published Online: April 20, 2017. doi:10.1001/jamaoto.2017.0124
Author Contributions: Dr Meltzer had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Meltzer, Gurushanthaiah, Meng, Tsai, Radler.
Acquisition, analysis, or interpretation of data: Meltzer, Klau, Meng, Tsai, Radler, Sundang.
Drafting of the manuscript: Meltzer, Sundang.
Critical revision of the manuscript for important intellectual content: Meltzer, Klau, Gurushanthaiah, Meng, Tsai, Radler.
Statistical analysis: Meltzer, Meng, Tsai, Radler, Sundang.
Obtained funding: Klau.
Administrative, technical, or material support: Tsai, Radler.
Supervision: Gurushanthaiah, Meng, Radler.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Additional Contributions: The authors thank Violeta Rabrenovich, MHA, The Permanente Federation , and Heather Qian, MBA, Kaiser Permanente National Health Plan and Hospital Quality, for their material support of this study. Jenni Green, MS, Health Information Technology Transformation and Analytics, provided writing and editing support. They were not compensated.
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