Monitoring performance in thyroidectomy: cumulative sum analysis of outcomes

BACKGROUND: Cumulative sum (CUSUM) analysis gives visual feedback on performance. It requires agreed benchmarks to compare binary outcomes. This process has not previously been applied to thyroidectomy. The objective of this study was to determine if CUSUM analysis can be employed to give feedback on performance of thyroidectomy. METHODS: A literature review to define the CUSUM analysis key performance indicators for thyroidectomy was performed. The key performance indicators for thyroid surgery were hematoma (return to theater for evacuation), hypocalcemia (corrected calcium <2.0 mmol/L), and vocal cord palsy (postoperative hoarseness with nasal endoscopic confirmation). Pre- and postoperative laryngoscopy was not routinely performed by all surgeons. Permanent was defined as duration longer than 6 months. A prospective audit of 216 patients undergoing thyroidectomy between January 2003 and December 2006 at the Geelong Hospital was completed. CUSUM charting of outcomes was performed after agreeing by consensus the boundaries of acceptable and unacceptable performance. RESULTS: Aggregate analysis of outcomes demonstrated acceptable performance across all clinical indicators. The incidence of temporary/permanent hypocalcemia and vocal cord palsy were 24%/2.6% and 3.2%/0.65%, respectively. About 1.39% of patients required evacuation of hematoma. CUSUM plotting of outcomes demonstrated acceptable performance. CONCLUSIONS: There is some variation of how standard outcome indicators for thyroidectomy are measured in the literature. A prospective audit using aggregate outcomes and CUSUM analysis has demonstrated that the performance of thyroid surgery at the Geelong Hospital was acceptable. These indicators and our methods of analysis could be used to monitor the performance of thyroid surgery at other hospitals.