Authors’ Response: The QoL-AGHDA Questionnaire—Can it Be Used to Assess Quality of Life in Hypopituitarism?

Ariel Barkan and Patricia Wren

Division of Endocrinology and Metabolism, University of Michigan Medical Center (A.B.), and Health Behavior and Health Education, School of Public Health, University of Michigan (P.W.), Ann Arbor, Michigan.

Address correspondence to: Ariel L. Barkan, M.D., Department of Internal Medicine/Division of Endocrinology and Metabolism, University of Michigan Medical Center, 3920 Taubman Center, Room 0354, Ann Arbor, Michigan 48109-0354.

To the editor:

Drs. Prieto and Webb’s critique asserts that the "Assessment of Growth Hormone Deficiency in Adults" (AGHDA) questionnaire is valid. The Stedman’s Medical Dictionary provides clear definition of validity: "the ability of test or procedure to show what it purports to show." Is the AGHDA a valid measure of quality of life (QoL) in patients with GH deficiency (GHD) according to this definition?

From the methodological point of view, the AGHDA questionnaire suffers from a multitude of defects. It can not be called "disease specific" because nowhere does it specify whether the subject attributes his/her diminished QoL to hypopituitarism per se. Perhaps, a hypopituitary person who is answering this questionnaire is also blind as a result of the pituitary tumor, or has an additional illness (diabetes, arthritis, depression, etc.). Would his/her low QoL be due to GHD or to an accompanying illness? The questions in the AGHDA were not operationalized according to specific domains such as opportunity, health perceptions, functional status, impairment, death/duration of life (see Patrick DL, Ericson P What constitutes quality of life? Concepts and dimensions. Clin Nutr, 1998; 7:53–63). The itemized answers were dichotomous (Yes/No), and, therefore, the degree of perceived impairment was not quantifiable. There was no time reference (i.e. over what period of time the subjects perceived their quality of life as decreased). Would a spat with the spouse the evening before the interview affect the subjects self-esteem? The mix of both adult- and childhood-onset subjects in the final questionnaire (despite the self-admitted fact that the latter had perfectly normal QoL) artificially lowered the score above which a subject was deemed to have QoL impairment.

From the practical point of view, the performance of this questionnaire as a baseline QoL instrument or as an indicator of the allegedly "salutary" effects of GH replacement was never demonstrated in a blinded, placebo-control setting. The alleged specificity of the AGHDA questionnaire for GHD was never tested in the populations with other chronic diseases such as depression, arthritis, diabetes, asthma, etc. The effects of pituitary surgery, cranial radiation, replacement therapy (or absence thereof) with other hormones, infertility, sexual dysfunction, cosmetic disfigurement, the need for a life-long follow-up, the stigma of wearing an ID necklace, etc. as independent factors determining QoL in patients with pituitary diseases were never assessed separately. Instead, impaired QoL in patients with pituitary diseases is blithely attributed to the GHD component of their illness. This is despite the facts that AGHDA, the supposedly GH-specific instrument, demonstrates normal QoL in individuals with the childhood onset of GHD, and that the degree of QoL impairment in adults bears no relation to their magnitude of GH deficiency. Finally, our study shows that AGHDA cannot even distinguish between GHD and GH excess. Thus, the AGHDA is neither sensitive nor specific, hence not valid; it does not show what it purports to show.

We agree with Drs. Prieto and Webb’s conclusion that the suitability of the AGHDA questionnaire to assess the QoL in hypopituitarism requires additional studies. Nothing less than a careful assessment of the specificity and sensitivity of AGHDA using a blinded, placebo-controlled design will be sufficient.

Received September 26, 2001.





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