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Original Studies |
Departments of Internal Medicine and Surgery, University of Michigan and Veterans Administration Medical Centers, Ann Arbor, Michigan 48109
Address all correspondence and requests for reprints to: Ariel Barkan, M.D., 3920 Taubman Center, Box 0354, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0354. E-mail: abarkan{at}umich.edu
| Abstract |
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| Introduction |
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As the performance of QoL-AGHDA during GH therapy had never before been tested in a double blind, placebo-controlled design, the contribution of placebo effects to a declining (improving) AGHDA score is uncertain. Thus, it is interesting to assess the performance of AGHDA in populations with widely different GH status. If AGHDA scores are different in this setting, the ability of this questionnaire to correctly identify changes in QoL during GH administration to hypopituitary adults would be supported. If the reverse is true, AGHDA should be further validated in double blind, placebo-controlled trials. To this end, we studied QoL-AGHDA scores in patients with severe hypopituitarism and in those with active acromegaly.
| Materials and Methods |
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Hypopituitarism
The group consisted of 9 women and 11 men, with a mean age of 49.4 ± 2.3 yr. Severe hypopituitarism in all 20 subjects was defined as a combination of a history of pathological process in the hypothalamic-pituitary area, the need for at least 3 replacement therapies (glucocorticoid, T4, and gonadal steroid), and plasma IGF-I that was low for the sex/age-adjusted normal range. Seven patients also required DDAVP to control their diabetes insipidus. The known duration of hypopituitarism was at least 4 yr. Five patients had nonfunctioning pituitary tumors, 1 had a macroprolactinoma, 3 had Rathkes cleft cyst, 4 had craniopharyngioma, 2 had Sheehans syndrome, and 1 patient each had tuberculous meningitis, meningioma, pituitary abscess, hypophysitis, and postpubertal panhypopituitarism of unknown etiology. Surgery was performed in 14 cases, and 6 of those patients also had XRT. The patient with macroprolactinoma was treated with dopamine agonists, and the remaining 19 patients received only replacement hormonal therapy.
Acromegaly
A total of 22 patients with acromegaly completed the questionnaire. The diagnosis of active disease was established clinically and confirmed by abnormally elevated plasma IGF-I levels in all of them. There were 7 women and 15 men with a mean age of 46.7 ± 3.3 yr. The duration of active acromegaly was estimated to be between 445 yr. Ten patients were newly diagnosed, and 12 were previously treated with transsphenoidal surgery. Five of them also had XRT, and 5 were taking dopamine agonists and/or somatostatin analogs. Five patients were taking standard replacement hormonal therapy in various combinations, and the remaining 17 were deemed not to have pituitary hormonal deficits.
Statistical analysis was performed using two-tailed Students t tests; P < 0.05 was considered significant. Data are presented as the mean ± SE.
| Results |
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The QoL-AGHDA score in normal controls was 3.3 ± 0.7 (range, 013), similar to the previously published data from other groups (8). This was significantly lower than in patients with hypopituitarism (10.6 ± 1.5; range, 023; P < 0.001) or in patients with active acromegaly (11.6 ± 1.6; range, 123; P < 0.001). There was no difference in QoL-AGHDA scores between patients with hypopituitarism and those with acromegaly (P > 0.5).
Due to a narrow range of plasma IGF-I levels in hypopituitary patients, the formal correlation analysis of AGHDA/IGF-I could not be performed with confidence. However, mean plasma IGF-I levels in the 12 patients with AGHDA scores equal to or below 13 (the highest value found in normal controls) and those in the 8 patients with AGHDA scores above 13 were similar (51.3 ± 9.8 vs. 41 ± 11.1 µg/L; P = 0.5). In patients with acromegaly, regression analysis between AGHDA scores and plasma IGF-I showed no correlation (r2 = 0.058). Newly diagnosed patients had higher plasma IGF-I (P < 0.05) than previously treated patients (828 ± 92 vs. 524 ± 52 µg/L), but their AGHDA scores were similar (10.8 ± 2.2 vs. 12.3 ± 2.3; P = 0.5).
| Discussion |
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Currently, improvement in the QoL emerges as a leading indication for GH therapy in hypopituitary adults. However, several unresolved questions cast doubt on the justification for this practice. First, several well controlled studies could not find evidence to support the existence of low QoL in that group (12, 13, 14). Second, QoL is an inherently subjective parameter and, as such, is very susceptible to the placebo effect. Importantly, no change in QoL was observed in several studies of GH replacement that employed a single blind, placebo-controlled design (3, 4). However, remarkable improvement in QoL was seen in the same patients once an open label administration of GH was commenced (3, 4). In one double blind placebo-controlled study of an 18-month duration, there was no change in QoL in GH-treated patients as measured by a multitude of sophisticated psychometric tests (14). In several other studies employing a double blind placebo-controlled design (5, 6, 7), GH was not superior to placebo, as demonstrated by the overall results of several psychometric instruments. Whether positive effects of GH in some of the multiple subdivisions of a particular instrument (5, 7) were due to the use of multiple t tests is uncertain. Obviously, a high incidence of GH-related side-effects, between 2470% (6, 7) probably unblinded the treatment arm, as stated by the researchers (6). One potential explanation for these findings would be that neither GHD nor GH sufficiency plays any role in determining the QoL. This is indirectly supported by a lack of correlation between QoL-AGHDA scores and the main biological mediator of GH activity, IGF-I, as seen by Murray et al. (9) and also in the patients presented here.
An alternative explanation would be that the QoL tests employed in the studies failing to document an effect of GH therapy were not specific for hypopituitarism. It has been asserted that GHD in hypopituitary adults affected QoL in a peculiar manner, and that only a psychometric instrument specifically designed for and validated in that group would be sensitive and specific enough to be reliably used in the research studies and in clinical practice (2, 8). That was the impetus behind the development of the QoL-AGHDA questionnaire. Using this instrument, low QoL in hypopituitary adults at diagnosis and its improvement after GH therapy have been demonstrated (9). The individuals with the lowest QoL (highest AGHDA scores) had the most improvement after GH treatment (9). The data presented here support the idea of higher QoL-AGHDA scores in adult hypopituitary subjects. This is not surprising, because any chronic illness requiring invasive treatments and life-long follow-up and associated with impaired bodily functions would probably worsen the QoL by any definition. Thus, the use of healthy individuals as a control group may not be entirely appropriate. Unfortunately, the performance of QoL-AGHDA was never assessed in patients with non-GH-related chronic illness. This is the likely reason why similarly high AGHDA scores were seen in this study in patients with severe GHD as well as in those with uncontrolled acromegaly and GH hypersecretion. Thus, it becomes conceptually difficult to attribute high AGHDA scores in patients with severe hypopituitarism and low IGF-I to GHD. Moreover, an improvement in AGHDA scores with GH treatment becomes biologically inexplicable. Importantly, the performance of QoL-AGHDA questionnaires in GH-treated hypopituitary adults had never been assessed in a double blind, placebo-controlled design. Thus, the existing reports of the salutary effects of GH in hypopituitarism that are based on QoL-AGHDA need to be viewed with reservation. Studies validating QoL-AGHDA for that purpose should be performed in a double blind, placebo-controlled fashion.
| Footnotes |
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Received September 19, 2000.
Revised November 20, 2000.
Revised December 28, 2000.
Accepted January 16, 2001.
| References |
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