Adoption of TSH Reflex algorithm in an Italian clinical laboratory.

BACKGROUND: TSH Reflex is an automated diagnostic algorithm which follows the rule "If ... then", in which the initial determination of TSH is followed by the determination of fT4, and possibly of fT3, if TSH is not within the reference limits. The aim of our study was to evaluate the results of the introduction and implementation of the test "TSH Reflex", which started in late 2013 in the hospital of Grosseto, comparing the requests of thyroid hormones for external patients, in 2012, 2014 and 2015.

METHODS: In our study we analyzed the number of thyroid tests prescribed in 2012, 2014 and 2015 and we calculated the increase in prescription of "TSH Reflex" from 2014 to 2015; the prescriptive appropriateness, after the introduction of the "TSH Reflex", through the ratios TSH/FT4, TSH/FT3 and the ratio "TSH Reflex"/TSH. Finally we calculated the total spending for the reagents in 2012, 2014 and 2015 and the consequent savings in euros (the costs of the reagents did not change during that time).

RESULTS: Requests for TSH decreased by 4.6% in 2014, compared to 2012 and by 5.4% in 2015 compared to 2014, with a 9.8% reduction in 2015 compared to 2012. The requests for FT4 decreased by 11.5%, comparing 2014 with 2012, by 5.3% comparing 2015 with 2014, with a 16.2% reduction in 2015 compared to 2012. The requests for FT3 decreased by 13.3% in 2014 compared to 2012 and by 8.4% in 2015 compared to 2014, with a 20.6% reduction in 2015 compared to 2012. The appropriateness, evaluated the indicator TSH/FT4, increased by 7.6%, comparing 2014 with 2012, and remained unchanged in 2015. In 2012 71,134 euros were spent, 63,998 euros in 2014, 60,055 euros in 2015, resulting in a saving of € 11,079 in 2015 compared to 2012. The spending for "TSH Reflex" should be subtracted (1,964 Euros in 2015) from the previous savings.

CONCLUSIONS: The improvement of the efficiency and the prescriptive appropriateness was better in 2014, the first year of implementation of the "TSH Reflex". The overall assessment suggests that the 2014 results are attributable to the letters that general practitioners received in December 2013, with a temporary increase of the use of the test. We need further analyses with the same indicators in order to assess the possibility of additional improvements in the future.