Christopher Symonds1, Gregory Kline1, Inelda Gjata1, Marianne Sarah Rose1, Maggie Guo1, Lara Cooke1, Christopher Naugler2. 1. Department of Medicine/Endocrinology (Symonds, Kline), Physician Learning Program (Gjata), Department of Clinical Neurosciences (Cooke) and Department of Pathology and Laboratory Medicine (Naugler), Cumming School of Medicine, University of Calgary; Health Services Statistical & Analytic Methods (Rose) and Alberta Precision Laboratories (Guo), Alberta Health Services, Calgary, Alta. 2. Department of Medicine/Endocrinology (Symonds, Kline), Physician Learning Program (Gjata), Department of Clinical Neurosciences (Cooke) and Department of Pathology and Laboratory Medicine (Naugler), Cumming School of Medicine, University of Calgary; Health Services Statistical & Analytic Methods (Rose) and Alberta Precision Laboratories (Guo), Alberta Health Services, Calgary, Alta. cjsymond@ucalgary.ca.
Abstract
BACKGROUND: Prescribing of levothyroxine and rates of thyroid function testing may be sensitive to minor changes in the upper limit of the reference range for thyroid-stimulating hormone (TSH) that increase the proportion of abnormal results. We evaluated the population-level change in levothyroxine prescribing and TSH testing after a minor planned decrease in the upper limit of the reference range for TSH in a large urban centre with a single medical laboratory. METHODS: Using provincial administrative data, we compared predicted volumes of TSH tests with actual TSH test volumes before and after a planned change in the TSH reference range. We also determined the number of new levothyroxine prescriptions for previously untreated patients and the rate of changes to the prescribed dose for those on previously stable, long-term levothyroxine therapy before and after the change in the TSH reference range. RESULTS: Before the change in the TSH reference range, actual and predicted monthly volumes of TSH testing followed an identical course. After the change, actual test volumes exceeded predicted test volumes by 7.3% (95% confidence interval [CI] 5.3%-9.3%) or about 3000 to 5000 extra tests per month. The proportion of patients with newly "abnormal" TSH results almost tripled, from 3.3% (95% CI 3.2%-3.4%) to 9.1% (95% CI 9.0%-9.2%). The rate of new levothyroxine prescriptions increased from 3.24 (95% CI 3.15-3.33) per 1000 population in 2013 to 4.06 (95% CI 3.96-4.15) per 1000 population in 2014. Among patients with preexisting stable levothyroxine therapy, there was a significant increase in the number of dose escalations (p < 0.001) and a total increase of 500 new prescriptions per month. INTERPRETATION: Our findings suggest that clinicians may have responded to mildly elevated TSH results with new or increased levothyroxine prescriptions and more TSH testing. Knowledge translation efforts may be useful to accompany minor changes in reference ranges.
BACKGROUND: Prescribing of levothyroxine and rates of thyroid function testing may be sensitive to minor changes in the upper limit of the reference range for thyroid-stimulating hormone (TSH) that increase the proportion of abnormal results. We evaluated the population-level change in levothyroxine prescribing and TSH testing after a minor planned decrease in the upper limit of the reference range for TSH in a large urban centre with a single medical laboratory. METHODS: Using provincial administrative data, we compared predicted volumes of TSH tests with actual TSH test volumes before and after a planned change in the TSH reference range. We also determined the number of new levothyroxine prescriptions for previously untreated patients and the rate of changes to the prescribed dose for those on previously stable, long-term levothyroxine therapy before and after the change in the TSH reference range. RESULTS: Before the change in the TSH reference range, actual and predicted monthly volumes of TSH testing followed an identical course. After the change, actual test volumes exceeded predicted test volumes by 7.3% (95% confidence interval [CI] 5.3%-9.3%) or about 3000 to 5000 extra tests per month. The proportion of patients with newly "abnormal" TSH results almost tripled, from 3.3% (95% CI 3.2%-3.4%) to 9.1% (95% CI 9.0%-9.2%). The rate of new levothyroxine prescriptions increased from 3.24 (95% CI 3.15-3.33) per 1000 population in 2013 to 4.06 (95% CI 3.96-4.15) per 1000 population in 2014. Among patients with preexisting stable levothyroxine therapy, there was a significant increase in the number of dose escalations (p < 0.001) and a total increase of 500 new prescriptions per month. INTERPRETATION: Our findings suggest that clinicians may have responded to mildly elevated TSH results with new or increased levothyroxine prescriptions and more TSH testing. Knowledge translation efforts may be useful to accompany minor changes in reference ranges.
Authors: David J Stott; Nicolas Rodondi; Patricia M Kearney; Ian Ford; Rudi G J Westendorp; Simon P Mooijaart; Naveed Sattar; Carole E Aubert; Drahomir Aujesky; Douglas C Bauer; Christine Baumgartner; Manuel R Blum; John P Browne; Stephen Byrne; Tinh-Hai Collet; Olaf M Dekkers; Wendy P J den Elzen; Robert S Du Puy; Graham Ellis; Martin Feller; Carmen Floriani; Kirsty Hendry; Caroline Hurley; J Wouter Jukema; Sharon Kean; Maria Kelly; Danielle Krebs; Peter Langhorne; Gemma McCarthy; Vera McCarthy; Alex McConnachie; Mairi McDade; Martina Messow; Annemarie O'Flynn; David O'Riordan; Rosalinde K E Poortvliet; Terence J Quinn; Audrey Russell; Carol Sinnott; Jan W A Smit; H Anette Van Dorland; Kieran A Walsh; Elaine K Walsh; Torquil Watt; Robbie Wilson; Jacobijn Gussekloo Journal: N Engl J Med Date: 2017-04-03 Impact factor: 91.245
Authors: Nicolas Rodondi; Wendy P J den Elzen; Douglas C Bauer; Anne R Cappola; Salman Razvi; John P Walsh; Bjørn O Asvold; Giorgio Iervasi; Misa Imaizumi; Tinh-Hai Collet; Alexandra Bremner; Patrick Maisonneuve; José A Sgarbi; Kay-Tee Khaw; Mark P J Vanderpump; Anne B Newman; Jacques Cornuz; Jayne A Franklyn; Rudi G J Westendorp; Eric Vittinghoff; Jacobijn Gussekloo Journal: JAMA Date: 2010-09-22 Impact factor: 56.272
Authors: Tinh-Hai Collet; Jacobijn Gussekloo; Douglas C Bauer; Wendy P J den Elzen; Anne R Cappola; Philippe Balmer; Giorgio Iervasi; Bjørn O Åsvold; José A Sgarbi; Henry Völzke; Bariş Gencer; Rui M B Maciel; Sabrina Molinaro; Alexandra Bremner; Robert N Luben; Patrick Maisonneuve; Jacques Cornuz; Anne B Newman; Kay-Tee Khaw; Rudi G J Westendorp; Jayne A Franklyn; Eric Vittinghoff; John P Walsh; Nicolas Rodondi Journal: Arch Intern Med Date: 2012-05-28