George L. Irvin

Risk adjustment of the postoperative morbidity rate for the comparative assessment of the quality of surgical care : Results of the National Veterans Affairs Surgical Risk Study

BACKGROUND The National Veterans Affairs Surgical Risk Study was designed to collect reliable, valid data on patient risk and outcomes for major surgery in the Veterans Health Administration and to report comparative risk-adjusted postoperative mortality rates for surgical services in Veterans Health Administration. STUDY DESIGN This cohort study was conducted in 44 Veterans Affairs Medical Centers. Included were 87,078 major noncardiac operations performed under general, spinal, or epidural anesthesia between October 1, 1991, and December 31, 1993. The main outcomes measure was all-cause mortality within 30 days after the index procedure. Multivariable logistic regression risk-adjustment models for all operations and for eight surgical subspecialties were developed. Risk-adjusted surgical mortality rates were expressed as observed-to-expected ratios and were compared with unadjusted 30-day postoperative mortality rates. RESULTS Patient risk factors predictive of postoperative mortality included serum albumin level, American Society of Anesthesia class, emergency operation, and 31 additional preoperative variables. Considerable variability in unadjusted mortality rates for all operations was observed across the 44 hospitals (1.2-5.4%). After risk adjustment, observed-to-expected ratios ranged from 0.49 to 1.53. Rank order correlation of the hospitals by unadjusted and risk-adjusted mortality rates for all operations was 0.64. Ninety-three percent of the hospitals changed rank after risk adjustment, 50% by more than 5 and 25% by more than 10. CONCLUSIONS The Department of Veterans Affairs has successfully implemented a system for the prospective collection and comparative reporting of risk-adjusted postoperative mortality rates after major noncardiac operations. Risk adjustment had an appreciable impact on the rank ordering of the hospitals and provided a means for monitoring and potentially improving the quality of surgical care.

A new approach to parathyroidectomy.

ObjectiveTo decrease the operative time for parathyroidectomy in patients with hypercalcemic (primary) hyperparathyroid disease, a combination of preoperative localization of a parathyroid tumor with an effective nuclear scan (scintigram) and intraoperative monitoring of parathyroid hormone (quick parathyroid hormone measurement) to ensure excision of all hyperfunctioning tissue was studied. Summary Background DataSummary Background Data many years, persistent hypercalcemia after parathyroidectomy (3% to 10%) has been constant and is usually due to the surgeons failure to remove all hyperfunctioning glands. A marked decrease in parathormone level after excision of a single large gland predicts operative success and a return to normal calcium levels. Conversely, persistent high levels of parathyroid hormone indicate excess secretion by another gland(s) and the need for further exploration. Recently Tc-99m-sestamibi (MIBI) scintigraphy was shown to be more effective in localizing parathyroid tumors than previous methods. A combination of both techniques could be useful to the surgeon if they improve the operative success rate and are cost-effective. MethodsParathyroidectomy was performed on 18 patients with primary hyperparathyroid disease, with tumors localized by MIBI scintigrams. When excision of the identified parathyroid gland was accomplished, the operation was terminated and quick parathyroid hormone was measured to confirm that all hyperfunctioning tissue was removed. ResultsResults patients with positive results of scintigram had successful parathyroidectomies confirmed by quick parathyroid hormone measurement with a cervical approach. Two patients with mediastinal tumors localized by MIBI scintigraphy could not be resected using this approach. One false-positive/false-negative scintigram was obtained. Compared with patients having parathyroidectomy without localization and hormone monitoring, the average operative time was shortened from 90 to 36 minutes. ConclusionsConclusions and successful excision of parathyroid tumors with confirmation that no other hyperfunctioning glands were present by quick parathyroid hormone monitoring can predict a return to normal calcium levels and a decrease in operative time in parathyroidectomy.

A new, practical intraoperative parathyroid hormone assay

BACKGROUND The clinical usefulness of intraoperative parathyroid hormone (PTH) monitoring has been shown using an immunoradiometric assay (IRMA) with several significant limitations. PTH measurement by immunochemiluminometric assay (ICMA) is a nonradioisotopic technique that is more practical for use during parathyroidectomy. METHODS Plasma from a 15-second microcentrifugation was mixed with 2 antibodies, incubated at 45 degrees C, shaken at 400 rpm for 7 minutes, washed and counted for 2 seconds on a portable luminometer; PTH level was reported in 10 minutes. RESULTS Sixteen patients had multiple samples taken during parathyroidectomy. PTH levels measured 5 minutes after excision of a suspected abnormal gland were compared with preoperative or preexicision samples and either confirmed complete excision or indicated the need for more exploration in each patient. Correlation of 88 ICMA samples with standard 24-hour IRMA controls was excellent (r = 0.9218, P < 0.0001). The sensitivity of the test in predicting postoperative calcium levels was 94%. CONCLUSION This new assay can serve as a very practical adjunct for the parathyroid surgeon.

Improved Success Rate in Reoperative Parathyroidectomy With Intraoperative PTH Assay

OBJECTIVE The clinical usefulness of preoperative localization and intraoperative PTH assay (QPTH) in primary hyperparathyroidism have been established. However, without the use of QPTH, the parathyroidectomy failure rate remains 5% to 10% in large reported series and is probably much higher in the hands of less experienced parathyroid surgeons. Persistent hypercalcemia requires another surgical procedure. The authors compared the outcomes in 50 consecutive patients undergoing more difficult secondary parathyroidectomy with and without the adjunctive support of QPTH. METHODS Two groups of similar patients underwent reoperative parathyroidectomy for failed surgery or recurrent disease. The successful return to normocalcemia in group I, with QPTH used to localize and confirm complete excision of all hyperfunctioning glands, was compared with group II, who did not have this intraoperative adjunct. RESULTS In 31/33 patients in group I, calcium levels returned to normal. With good preoperative localization studies, 17 patients underwent successful straightforward parathyroidectomies as predicted by QPTH. In the other 14 patients, QPTH assay proved extremely beneficial by facilitating localization with differential venous sampling; measuring the increase in hormone secretion after massage of specific areas; recognizing suspicious nonparathyroid tissue excised without a decrease in hormone levels, avoiding frozen-section delay; and correctly identifying the excision of abnormal tissue despite false-positive/false-negative sestamibi scans. In group II, who underwent surgery before QPTH was available, 4 of 17 patients (24%) remained hypercalcemic after extensive reexploration. CONCLUSION With the intraoperative hormone assay used to facilitate localization and confirm excision of all hyperfunctioning tissue, the success rate of reoperative parathyroidectomy has improved from 76% to 94%.

Quick Intraoperative Parathyroid Hormone Assay: Surgical Adjunct to Allow Limited Parathyroidectomy, Improve Success Rate, and Predict Outcome

Intraoperative parathyroid hormone (PTH) assay (QPTH) has made possible less invasive operative approaches in the treatment of primary hyperparathyroidism with stated advantages. When compared to the traditional bilateral neck exploration (BNE), only the targeted, hypersecreting gland is excised, leaving in situ non-visualized but normally functioning parathyroids. The QPTH-guided limited parathyroidectomy (LPX) must be able to identify multiglandular disease (MGD), predict a successful outcome, and have a low recurrence rate. In our series, 421 patients who underwent LPX were compared to 340 undergoing BNE; all operative failures and patients followed for 6 months or longer were included. Operative failure occurred if serum calcium and PTH levels were elevated within 6 months of parathyroidectomy. Multiglandular disease was defined in the LPX group as more than one gland excision guided by QPTH or operative failure after removal of a single abnormal gland; in the BNE group it was defined as excision of more than one enlarged gland. Recurrence was defined as elevated calcium and PTH after 6 months of eucalcemia. Operative failure and MGD rates were compared using chi-squared analysis. The method of Kaplan-Meier and the log-rank test were used to compare recurrence rates. Operative success was seen in 97% of LPX patients and in 94% of the BNE group (p = 0.02). Multiglandular disease was identified in 3% of LPX patients and 10% of BNE patients (p < 0.001). There was no statistical difference in the overall recurrence rates (p = 0.23). The QPTH-guided parathyroidectomy identifies MGD and allows an improved success rate with the same low recurrence rate when compared to the results of BNE.

Operative monitoring of parathyroid gland hyperfunction

Abstract With a 20-year experience of more than 700 parathyroidectomies, our persistent hypercalcemic postoperative failure rate of 7% has remained constant. Reasons for failure have been misdiagnosis or inability of the surgeon to detect and excise all hypersecreting glands. We have modified a commercially available immunoradiometric assay for intact parathyroid hormone (PTH) resulting in a 15-minute turnaround time. Since intact PTH has a half-life measured in minutes, whole blood samples taken 10 minutes after gland excisions were monitored intraoperatively to confirm significant changes in circulating hormone. Quantitative evidence that all hyperfunctioning parathyroid tissue had been ablated during operation was obtained in 19 of 21 patients. Less than four glands each were identified in 53% of these patients. The PTH “quick” test correctly pointed to an inadequate excision requiring further parathyroid ablation in two patients, made bilateral neck exploration unnecessary in two patients who had previously undergone parathyroidectomy, and predicted persistent hypercalcemia in two patients with complications.

Progress in the operative management of sporadic primary hyperparathyroidism over 34 years.

Background:Progress in the diagnosis, localization of abnormal parathyroids, and intraoperative management of primary hyperparathyroidism has been observed over the past 34 years. The goal of this study is to report the outcome of patients undergoing 2 different operative approaches in a single institution, showing the evolution of surgical management of sporadic primary hyperparathyroidism (SPHPT). Methods:Parathyroidectomy was performed in 890 (827 initial, 63 reoperative) patients with SPHPT using 2 different approaches: traditional bilateral neck exploration (BNE, n = 396) or limited parathyroidectomy guided by parathormone dynamics (LPX, n = 494). Seven hundred eighteen patients (335 BNE, 383 LPX) followed ≥ 6 months or identified as operative failures were studied. Operative failure is defined as hypercalcemia and high intact (1–84) parathyroid hormone molecule (iPTH) within 6 months after operation. Successful parathyroidectomy is normocalcemia for 6 months; hypercalcemia and elevated iPTH after this time is recurrent hyperparathyroidism. Results:There were 20 (6%) of 335 operative failures in the BNE group and 11 (3%) of 383 failures in the LPX group (P = 0.04). The incidence of multiglandular disease (MGD) determined by gland size (10%) versus hormone hypersecretion (3%) was statistically different (P < 0.001). Since most of the recurrences occurred later than 30 months, the incidence of recurrent hyperparathyroidism in patients followed for longer than 2.5 years was 4% (11/287) in the BNE group (average, 11.5 years) and 3% (5/183) in the LPX group (average, 4.2 years). Conclusion:LPX, with its reported advantages of minimal dissection, shorter operative time, and use in ambulatory settings, compares favorably with the traditional BNE. Parathyroidectomy guided by parathormone dynamics has an improved success rate and should be considered as a standard operative approach in SPHPT.

Intraoperative parathyroid hormone monitoring as an adjunct to parathyroidectomy

BACKGROUND Parathyroidectomy has a success rate of greater than 95% in the hands of experienced surgeons. To maintain this result in a more cost-effective way, intraoperative monitoring of intact parathyroid hormone (iPTH) has been used to decrease operative times. This technique signals when all hyperfunctioning tissue has been excised or when further dissection is necessary. METHODS Eighty-nine consecutive patients with hyperparathyroidism had plasma samples measured for iPTH levels during parathyroidectomy. Nine patients had previous neck explorations. Perioperative iPTH measurements using immunochemiluminescent assays with a turnaround time of 10 minutes were done after excision of each suspected abnormal parathyroid gland. RESULTS All patients except one returned to and maintained normal calcium levels during the follow-up period of 8 months (range, 1 to 25 months). Prediction of postoperative calcium levels by means of quick immunochemiluminescent assay has a sensitivity of 97%, specificity of 100%, and an overall accuracy of 97%. Specific influence on surgical judgment was noted in four patients with multiglandular disease, in seven with difficult localization problems, and in one patient in whom the hyperfunctioning parathyroid tissue was not recognized. Monitoring the plasma iPTH levels during parathyroidectomy directly aided the surgeons operative approach in these 12 patients. CONCLUSIONS Intraoperative iPTH assay is useful with predictive accuracy of 97%. It influenced or changed the operative approach in 13% of patients.

Incidence of multiglandular disease in primary hyperparathyroidism determined by parathyroid hormone secretion

BACKGROUND Successful parathyroidectomy depends on recognition and excision of all hyperfunctioning parathyroid glands. Because histologic definition is limited, multiglandular disease (MGD) is usually determined grossly by means of estimation of gland size and the experience of the surgeon, resulting in frequency varying from 8% to 33%. Normalization of elevated intraoperative intact parathyroid hormone (iPTH) levels after excision of all hyperfunctioning glands is necessary for postoperative normocalcemia and indicates normal secretion of remaining parathyroids. Abnormal hormone secretion measured during operation has been used to define the extent of excision and the incidence of MGD. METHODS One hundred ten consecutive parathyroidectomy patients with no previous neck surgery or history of multiple endocrine neoplasia had intraoperative iPTH assays performed before and after excision of any suspected abnormal parathyroid gland(s). A drop in iPTH level after gland excision predicted postoperative normal calcium levels. RESULTS All patients except one had normalization of serum calcium levels (average follow-up, 15 months). One hundred five patients had only one hyperfunctioning gland removed, and all have remained normocalcemic. Five (5%) patients had more than one gland involved: four had two or more hyperfunctioning parathyroids and one patient, who had a large parathyroid cyst removed, remained hypercalcemic. CONCLUSIONS By using a biochemical assay, instead of estimated size, to predict which parathyroid glands are hypersecreting, the incidence of MGD in primary hyperparathyroidism was found to be 5%.

The evolution of parathyroidectomy failures

BACKGROUND Reported operative failure rates for primary hyperparathyroidism range from 5% to 10%. Failure has been due to multiglandular disease, ectopic parathyroid glands, errors in frozen section, and missed diagnoses. Recently, our operative approach has changed from bilateral cervical exploration to direction by preoperative localization and intraoperative quick parathyroid hormone assay. The purpose of this study is to examine the causes and rates of failure in this evolving approach to parathyroidectomy. METHODS Among 447 consecutive cases of primary hyperparathyroidectomy, 20 operative failures were examined. Three different operative approaches were compared with respect to causes and rates of failure. RESULTS From 1969 to 1989, with bilateral neck exploration, failure was due to missed diagnoses, ectopic glands, multiglandular disease, and unknown causes, with a failure rate of 5%. From 1990 to 1993, with bilateral neck exploration and quick parathyroid hormone assay, failure was due to ectopic mediastinal glands, misinterpretation of frozen section, and operative judgment, with a failure rate of 10%. From 1993 to 1998, with preoperative localization and quick parathyroid hormone assay, the two operative failures (1.5%) were due to operative judgment and misinterpretation of the quick parathyroid hormone assay. CONCLUSIONS The new surgical approach combining preoperative localization studies and intraoperative parathyroid hormone monitoring has eliminated the most common causes of parathyroidectomy failure and has significantly decreased the operative failure rate.