OBJECTIVES: Regulatory agencies demand QALYs as evidence of effectiveness in economic evaluation. This is a challenge for clinical studies in which outcomes are measured using condition-specific instruments that lack the required measurement properties. This study aims to provide a model for deriving EQ-5D utilities directly from the QoL-AGHDA. These estimates were used to calculate QALY deficit and treatment effects in adults with GHD in relation to the general population values. METHODS: A UK postal survey captured QoL-AGHDA (a condition-specific measure for patients with GHD) and EQ-5D responses from a broadly representative sample of the general population (n=921). These data were used to construct two-step regression model (R2 =0.42). In the first, TTO-weighted ED-5Dindex was the dependent variable and yes/no responses to all 25 QoL-AGHDA items were coded as dichotomous dummy variables (xi). In the second step utilities were computed as follows: QoL-AGHDA utility = b0 + c*age+? bi*xi + ei. QoL-AGHDA utility at yearly visits for 894 UK patients followed in the KIMS database was computed using the same regression model. Subsequently the mean QALY over time were compared to baseline values and assessed in relation to the cross-sectional age/gender population values. RESULTS: Health related quality of life measured by QoL-AGHDA utility in patients prior to GH replacement differed significantly from age/gender-matched values in the general population (0.67 vs. 0.85, p<0.0001). After the first year of treatment the deficit was reduced to – 0.07. Despite a dramatic improvement during the first year of treatment, patients' health status remained significantly different from general population reference values (p<0.001) over the course of their treatment. Nevertheless, a mean undiscounted gain from baseline of 0.32 QALYs was seen in the treated patients, corresponding to 0.08 QALYs per year. CONCLUSION: Estimates of treatment benefit for use in economic evaluation can be successfully derived from condition-specific measures.