Introduction: There is little evidence that the addition of interpretative comments to biochemistry reports can influence outcome for patients. Interpretative comments on thyroid function test (TFT) requests were introduced in Hull in August 1999, providing the opportunity to determine whether feedback on hypothyroid patients taking thyroxine could lead to a reduction in the proportion whose thyroxine was inadequately replaced.
Patients and methods: The study comprised 15 584 TFT requests, made from 1 August 1999 to 30 August 2002 by general practitioners (GPs), for 8281 patients taking thyroxine. Under-replacement of thyroxine, defined as a TSH concentration above the upper reference limit (i.e. 4.7 mU/L), was usually commented on in the biochemical report.
Results: In the first, second and third years following introduction of interpretative comments, the proportions of samples with a TSH concentration of >4.7 mU/L were 21.3%, 17.6% and 16.6%, respectively (chi(2)(trend) = 43.1, P <0.0001). The proportion with a TSH concentration of <0.1 mU/L showed a more modest change, from 12.5% in year 1 to 14.0% and 14.8% in years 2 and 3, respectively (chi(2)(trend) = 22.3, P <0.0001).
Conclusion: This study shows that in the three years following the introduction of interpretative comments there was a 22% reduction in the number of GPs' samples indicating thyroxine under-replacement. It seems likely that these data provide evidence that comments can indeed influence the biochemical outcome of patients.