Molecular Testing for Bethesda III Thyroid Nodules: Trends in Implementation, Cytopathology Call Rates, Surgery Rates, and Malignancy Yield at a Single Institution.

Background: Molecular testing (MT) has become standard practice to more accurately rule out malignancy in indeterminate Bethesda III (BIII) thyroid lesions. We sought to assess the adoption of this technology and its impact on cytology reporting, malignancy yield, and rates of surgery across community and academic sites affiliated with a tertiary medical center. Methods: We performed a retrospective cross-sectional study including all fine-needle aspirations (FNAs) analyzed at our institution from 2017 to 2021. We analyzed trends in MT utilization by platform and by community or academic site. We compared BIII call rates, MT utilization rates, rates of subsequent surgery, and malignancy yield on final pathology before and after MT became readily available using chi-square analysis and linear regression. Results: A total of 8960 FNAs were analyzed at our institution from 2017 to 2021. There was broad adoption of MT across both community and academic sites. There was a significant increase in both the BIII rate and the utilization of MT between the pre- and post-MT periods (p < 0.001 and p < 0.001). There was no significant change in the the malignancy yield on final pathology (57.1% vs. 50.0%, p = 0.347), while the positive predictive value of MT decreased from 85% to 50% (p = 0.008 [confidence interval 9.5-52.5% decrease]). Conclusions: The use of MT increased across the institution over the study period, with the largest increase seen after a dedicated pass for MT was routinely collected. This increased availability of MT may have led to an unintended increase in the rates of BIII lesions, MT utilization, and surgery for benign nodules. Physicians who use MT should be aware of potential consequences of its adoption to appropriately counsel patients.

Does the Adoption of Molecular Testing Cause Decreased Thyroidectomy Rates in a National Cohort? A Quasiexperimental Study of High- Versus Low-Adoption States.

Background: Over the last decade, the utilization of molecular testing (MT) for the evaluation of thyroid nodules has increased. Rates and patterns of adoption of MT and its effect on thyroidectomy rates nationally are unknown. Varying rates of MT adoption at the state level provide an opportunity to study the effects of MT on thyroidectomy rates using a quasiexperimental study design. Methods: We performed a retrospective analysis of American adult patients in the Merative™ MarketScan® Research Databases who underwent thyroid fine-needle aspiration (FNA) from 2011 to 2021. MT included commercially available DNA and RNA platforms and traditional targeted mutational analysis. Interrupted time series analysis was used to evaluate the inflection of MT adoption and thyroidectomy rates after 2015. Difference-in-differences (DID) analysis was used to causally analyze the effect of MT adoption on thyroidectomy rates in high-adoption (at least a 10% increase in MT utilization) versus low-adoption states (no more than 5% increase in MT utilization) from 2015 to 2021. Results: We identified 471,364 patients who underwent thyroid FNA. The utilization of MT increased over the study period from 0.01% [confidence interval, CI: 0.00% to 0.02%] to 10.1% [CI: 9.7% to 10.5%], in 2021, with an immediate (ß2 = 1.61, p = 0.002) and deeper (ß3 = 0.6, p < 0.001) increase in MT adoption after 2015. Utilization of MT was lower in black patients, the elderly, rural areas, and patients with Medicaid (p < 0.05). Thyroidectomy rates were inversely correlated with MT utilization (r = -0.98, p < 0.0001). From 2015 to 2021, the average MT utilization rate increased from 2.4% to 15.3% in high-adoption states and 1.6% to 5.6% in low-adoption states. In low-adoption states, thyroidectomy rates decreased more but to similar levels (18.5-13.2%) compared with high-adoption states (15.9-13.4%) with an adjusted DID rate of -3.3% [CI -5.6% to -0.8%]. Conclusions: The acceleration in adoption of MT after 2015 likely coincides with the publication of American Thyroid Association guidelines. Black, elderly, and rural patients are less likely to receive MT. Although thyroidectomy rates were inversely correlated with MT utilization, our study suggests that this correlation is not causal. The effect of MT on thyroidectomy rates may be overshadowed by decreasing aggressiveness of thyroid nodule evaluation.

A national study of postoperative thyroid hormone supplementation rates after thyroid lobectomy.

BACKGROUND: The American Thyroid Association updated guidelines in 2015 to allow lobectomy for low-risk thyroid cancers. The objectives of this study were (1) to determine thyroid hormone supplementation rates after lobectomy and (2) to evaluate the effect of the American Thyroid Association guideline change on lobectomy and hormone supplementation rates among thyroid cancer patients. METHODS: The Merative MarketScan Databases was used to identify adult (≥age 18) patients who underwent thyroidectomy for benign nodules or thyroid cancer. The association between indication for surgery and postoperative thyroid hormone supplementation was examined using χ2 analyses and multivariable logistic regression models. Among patients with thyroid cancer, lobectomy and hormone supplementation rates were compared in the periods before (2008-2015) and after the guideline change (2016-2019). RESULTS: Of the 81,926 patients identified, 33,756 (41.2%) underwent thyroid lobectomy, 45,104 (55.1%) underwent total thyroidectomy, and 3,066 (3.7%) underwent completion thyroidectomy. Patients who underwent lobectomy for malignancy were significantly more likely to require hormone supplementation (59.3% vs 39.4% [P < .001], adjusted odds ratio 2.34 [95% confidence interval 2.20-2.48]) compared to those with benign disease. Compared to the 2008 to 2015 period, the proportion of patients who underwent lobectomy for thyroid cancer was higher in the 2016 to 2019 period (34.3% vs 30.3%, P < .001), with fewer patients requiring completion thyroidectomy (25.6% vs 29.8%, P < .001) and thyroid hormone supplementation (56.9% vs 60.1%, P = .04). CONCLUSION: The postoperative thyroid hormone supplementation rate was significantly higher in patients who had thyroid cancers compared to benign diseases. After the American Thyroid Association guidelines changed, lobectomy rates increased significantly without a concomitant increase in the completion of thyroidectomy.

Phenoxybenzamine is no longer the standard agent used for alpha blockade before adrenalectomy for pheochromocytoma: A national study of 552 patients.

BACKGROUND: Phenoxybenzamine has been the standard agent for blockade before adrenalectomy for pheochromocytoma. However, high cost and limited availability have hampered its use. This study investigated whether other agents have supplanted the use of phenoxybenzamine as the first-line agent for alpha blockade in pheochromocytoma. METHODS: We performed a retrospective analysis of patients in the IBM MarketScan Database who underwent adrenalectomy for pheochromocytoma (2008-2019). Patients were categorized as having been blocked with phenoxybenzamine, selective alpha blockers, calcium channel blockers and/or beta blockers, or none of the above. The outcomes included prescription costs, perioperative costs, and length of stay. RESULTS: A total of 552 patients were identified; 58.7% were female, and the median age was 49 (interquartile range 40-57) years. In total, 291 (52.7%) patients were blocked with phenoxybenzamine, 114 (20.7%) with selective alpha blockers, 42 (7.6%) with only calcium channel blockers and/or beta blockers, and 76 (13.8%) with none. The proportion of patients blocked with phenoxybenzamine decreased from 71.0% in 2008 to 21.2% in 2019. The proportion of patients blocked with selective alpha blockers increased from 6.5% in 2008 to 42.4% and in 2019. The median cost of phenoxybenzamine increased from $722 (interquartile range $441-$1,514) in 2008 to $9,616 (interquartile range $5,049-$16,373) in 2019 (P < .001). Length of stay (2 [interquartile range 1-4] days vs 2 [interquartile range 0-3] days) and total perioperative costs ($24,250 [interquartile range $17,462-$33,849] vs $22,098 [interquartile range $16,341-$29,178] between phenoxybenzamine and selective alpha blocker groups were similar. CONCLUSION: There has been a significant shift away from phenoxybenzamine for preoperative blockade before resection of pheochromocytoma. Selective alpha blockers and calcium channel blockers are increasingly used, likely due to reduced costs, without compromised length of stay or intensive care unit admission.

If the price is right: Cost-effectiveness of radiofrequency ablation versus thyroidectomy in the treatment of benign thyroid nodules.

BACKGROUND: Radiofrequency ablation is an emerging technology in the United States to treat benign thyroid nodules. The cost-effectiveness of radiofrequency ablation in comparison with traditional thyroidectomy is unknown. METHODS: A patient-level state transition microsimulation decision model was constructed comparing radiofrequency ablation with lobectomy in the management of benign thyroid nodules. Our base case was a 45-year-old woman with a solitary 30-cm3 nodule. Estimates of health utilities, complications, and mortality were obtained from the literature, and costs were estimated using Medicare reimbursement data. The primary outcomes of interest included total cost, quality-adjusted life years, and incremental cost-effectiveness ratios. All model estimates were subjected to 1-way sensitivity analyses to identify factors that strongly influence cost-effectiveness. A probabilistic sensitivity analysis was run across 1 million simulations to gauge outcome confidence with a willingness-to-pay threshold set at $100,000/quality-adjusted life year. RESULTS: Radiofrequency ablation was assumed to cost $5,000, with an initial success rate of 78%. Patients with volume reduction ratio <50% underwent a second treatment of radiofrequency ablation. Radiofrequency ablation represented the dominant strategy, yielding 21.31 quality-adjusted life years for a total cost of $16,563 in comparison to lobectomy, which yielded 21.13 quality-adjusted life years for a total cost of $19,262. In a 1-way sensitivity analysis varying the cost of radiofrequency ablation across of range of values, the radiofrequency ablation strategy remained cost-effective until the cost of radiofrequency ablation exceeded $12,330 at willingness-to-pay $50,000 or $17,950 at willingness-to-pay $100,000. CONCLUSION: Radiofrequency ablation is a cost-effective strategy in the treatment of benign thyroid nodules but is most sensitive to the cost of radiofrequency ablation.

The effect of chronic kidney disease on intraoperative parathyroid hormone: A linear mixed model analysis.

BACKGROUND: Reduced creatinine clearance is an indication for surgery in asymptomatic primary hyperparathyroidism, and a significant proportion of patients undergoing parathyroidectomy have chronic kidney disease. The purpose of this study was to evaluate the kinetics of intraoperative parathyroid hormone decline during parathyroidectomy in patients who have chronic kidney disease compared with those with who have normal renal function. METHODS: This is a single-center, retrospective study of patients with primary hyperparathyroidism undergoing parathyroidectomy (n = 646). Patients were grouped based on estimated glomerular filtration rate greater than (normal renal function) or less than (chronic kidney disease) 60 mL/min/1.73m2. All patients had intraoperative parathyroid hormone monitoring and ≥6-month postoperative serum studies to confirm surgical cure. Intraoperative parathyroid hormone kinetic curves were analyzed using a linear mixed model. RESULTS: Despite similar pre-excision values, patients with chronic kidney disease had significantly higher intraoperative parathyroid hormone values at 5 minutes (76 vs 58 pg/mL, P = .02) and 10 minutes (54 vs 37 pg/mL, P = .004) postexcision. No significant difference was observed in whether patients met Miami criterion by 5 minutes (chronic kidney disease 71%, normal renal function 78%, P = .255) or by 10 minutes (chronic kidney disease 95%, normal renal function 96%, P = .751) postexcision. Using a linear mixed model, glomerular filtration rate did not have a significant effect on the change in intraoperative parathyroid hormone over time. CONCLUSION: Patients with chronic kidney disease had significantly higher postexcision intraoperative parathyroid hormone levels. However, renal function did not affect the change in intraoperative parathyroid hormone over time, nor did renal function ultimately affect the likelihood of meeting the Miami criterion. Intraoperative parathyroid hormone monitoring remains useful in this population, although additional time points may be needed to observe normalization of values.

Biochemical Profile Affects IOPTH Kinetics and Cure Rate in Primary Hyperparathyroidism.

BACKGROUND: Recently, normocalcemic (NC) and normohormonal (NH) variants of primary hyperparathyroidism (pHPT) have been described, with distinct biochemical profiles from the typical high serum calcium and parathyroid hormone (PTH) levels. Here, we investigate whether biochemical profile affects cure rate, as well as the kinetics of intraoperative PTH (IOPTH). METHODS: This is a single-center, retrospective study of pHPT patients undergoing parathyroidectomy. Patients were grouped based on preoperative calcium and PTH levels into typical, NC (normal calcium, elevated PTH, no evidence of secondary hyperparathyroidism), and NH (elevated calcium, unsuppressed PTH) biochemical profiles. All patients had IOPTH monitoring and ≥6-month post-op serum studies to confirm surgical cure. Patient variables were analyzed with Kruskal-Wallis test and Chi-square analysis. IOPTH kinetic curves were analyzed using a linear mixed model. RESULTS: From June 2006 to October 2014, 646 patients met inclusion criteria. Biochemical profile was typical in 460 patients (71%), NC in 101 (16%), and NH in 85 (13%). IOPTH levels were higher at all time points in typical patients, p < 0.001. Surgical cure rates were significantly lower for NC patients (90.1%) than for typical (98.5%) or NH patients (97.7%), p < 0.001, although a stricter criteria for cure was used in this group (normal calcium AND normal PTH). In a multivariable linear mixed model, NC patients had a significantly slower rate of IOPTH decline (p < 0.001 at 10 min). CONCLUSIONS: Here, we better characterize the atypical variants of pHPT. Using a stricter definition of cure in the NC variant, these patients have a lower surgical cure rate than typical or NH variants in pHPT. The IOPTH curve is affected by biochemical profile, with both NC and NH patients having lower absolute values and NC patients having a slower decline.

Vitamin D Does Not Affect Intraoperative Parathyroid Hormone Kinetics: A Mixed Linear Model Analysis.

BACKGROUND: Intraoperative parathyroid hormone (ioPTH) monitoring is used to confirm completeness of resection in patients undergoing parathyroidectomy for primary hyperparathyroidism (pHPT). Though there is an inverse relationship between vitamin D and parathyroid hormone (PTH), previous studies have suggested that 25-hydroxyvitamin D (25OHD) level does not affect the likelihood of meeting the Miami criterion. Here, we further investigate whether preoperative 25OHD level affects ioPTH kinetics. METHODS: This is a retrospective case-control study of patients undergoing parathyroidectomy for pHPT at a tertiary referral center. Patients were categorized based on preoperative 25OHD level as vitamin D deficient (≤ 20 ng/mL), insufficient (21-30 ng/mL), or sufficient (>30 ng/mL). Differences in baseline characteristics were analyzed with Kruskal-Wallis H test or chi-square analysis. ioPTH kinetic curves were analyzed using a log-transformed mixed linear model with subject-level random effects. Significance was set at P < 0.05. RESULTS: Among 630 patients who met inclusion criteria, there was a significant difference in ioPTH between groups at baseline (P < 0.001), but not at any other time point. As a continuous variable, as well as a categorical variable, in a mixed linear model, vitamin D had no significant effect on ioPTH kinetics. CONCLUSIONS: Despite a difference in preoperative and baseline PTH levels, preoperative 25OHD had no significant effect on ioPTH kinetics. Therefore, ioPTH assays can be used and interpreted uniformly, regardless of patients' vitamin D status.

Short chain fatty acids stimulate feline colonic smooth muscle contraction.

The effect of short chain fatty acids (SCFA) on feline colonic smooth muscle contraction was evaluated in vitro. Colonic tissue was obtained from seven healthy male and female adult cats and seven healthy male and female kittens. Longitudinal and circular colonic smooth muscle strips from proximal and distal colon were incubated with SCFA (acetate, butyrate and propionate; 1-100mM). SCFA-induced contractions were compared to responses obtained using maximal concentrations (10(-4)M) of acetylcholine (ACh). The calcium dependence of the SCFA response was investigated by incubating with nifedipine (1 microM) or verapamil (1 microM). Acetate, butyrate and propionate elicited isometric stress responses (0.25-1.98 x 10(4)N/m(2)) in longitudinal, but not circular, smooth muscle from both the proximal and distal colon of adult cats. Maximal responses were attained at 50 and 100mM SCFA. Maximal butyrate and propionate responses were 29 and 19% of the maximal ACh response (10(-4)M), respectively. Acetate was least effective in stimulating contractile responses. Nifedipine and verapamil abolished all responses. Contractile responses in kittens were similar to those observed in adult cats, but were smaller in amplitude. Results of these studies have shown that SCFA stimulate longitudinal colonic smooth muscle contractions in kittens and adult cats in vitro. These SCFA-induced contractions involve activation of calcium influx. These in vitro findings may account for some of the effects of dietary fiber on feline colonic motility in vivo.

Effect of short-chain fatty acids on contraction of smooth muscle in the canine colon.

OBJECTIVE: To determine effects of short-chain fatty acids (SCFA) on canine colonic smooth muscle. SAMPLE POPULATION: Colonic tissue obtained from 14 healthy dogs. PROCEDURE: Short-chain fatty acid (SCFA; acetate, propionate, and butyrate; 1 to 100 mmol/L)-induced contractions were compared with responses obtained with acetylmethylcholine (AMCh; 10(-4) mol/L). Roles of enteric neurons, cholinergic receptors, calcium stores in the sarcoplasmic reticulum, and extracellular calcium in the SCFA-induced responses were investigated by incubating muscle strips with tetrodotoxin (1 micromol/L), atropine (1 micromol/L), ryanodine (10 micromol/L), nifedipine (1 micromol/L), ethylene glycol-bis (beta-aminoethylether)-N,N,N',N'-tetra-acetate (EGTA; 0.1 mmol/L), or an extracellular calcium-depleted (zero extracellular calcium) solution prior to the addition of propionate or butyrate. RESULTS: Incubation with SCFA elicited isometric stress responses (0.25 to 2.15 x 10(4) N/m2) in colonic longitudinal smooth muscle. Maximal responses to butyrate and propionate (50 mmol/L) were 37 and 23%, respectively, of the maximal AMCh response. Acetate was least effective in stimulating contractile responses. Tetrodotoxin and atropine did not affect SCFA-induced contractions. Nifedipine and zero extracellular calcium solution abolished responses to butyrate and propionate, whereas EGTA attenuated (> 60%) but did not abolish those responses. Ryanodine did not affect SCFA-induced contractile responses. The SCFA did not affect colonic circular smooth muscle. CONCLUSIONS AND CLINICAL RESPONSE: The SCFA stimulate longitudinal but not circular colonic smooth muscle contractions via a direct effect on smooth muscle. The mechanism of the SCFA effect appears to involve the influx of extracellular calcium. These findings may account for some of the effects of fiber on canine colonic motility [corrected].