The development, reliability and validity of a disease specific quality of life model for adults with growth hormone deficiency.

Abstract

Adults with GH deficiency frequently complain of lack of energy, fatigue, social isolation and problems with sexual relationships resulting in a low perceived quality of life. Previous studies of quality of life (QOL) in GH deficient adults have involved small numbers of patients and used measures not specifically designed for this patient population. We have devised a health related QOL model specifically designed for use in adults with GH deficiency and to assess the impact of future GH replacement therapy. Six measurements were chosen for inclusion in the model. Two were adapted for use after clinical interviews with 12 adult GH deficient patients: the Impact and the Life Fulfilment scales. The others were the Nottingham Health Profile, the Hospital Anxiety and Depression Scale, the Self-Esteem Scale and the Mental Fatigue Questionnaire. The reliability of the 6 measures was assessed by 2 methods: test re-test correlation and internal consistency (Cronbach's alpha). The validity of the Impact and Life Fulfilment scales was assessed by correlation with the other 4 scales. Questionnaires were completed by 32 adults with hypothalamic pituitary disorders and GH deficiency (11 male, mean age 35.1 years), with a stimulated maximum serum GH response less than 10 mU/l (mean 2.96). Two had previously received GH injections in childhood. The questionnaires were also completed by 32 age and sex matched control subjects. The 6 scales had test re-test correlations of 0.70-0.92 indicating reliability over time. The Impact and Life Fulfilment Scales and the Mental Fatigue Questionnaire had Cronbach's alpha scores of greater than 0.6 indicating their potential for use in clinical trials. The Impact and Life Fulfilment scales correlated significantly with many physical and psychological domains from the other 4 scales indicating these were valid in the assessment of health related QOL in GH deficient adults. Compared to the controls the patients with GH deficiency were significantly psychosocially disadvantaged in terms of depression, self-esteem, mental fatigue and life fulfilment. The results of the reliability and validity studies indicate that this health related quality of life model for use with adults with GH deficiency is a potentially valid and reliable tool that could be used to assess the effect of GH treatment.