A paradigm shift in the monitoring of patients with acromegaly: last available growth hormone may overestimate risk.
BACKGROUND
Acromegaly is associated with reduced life expectancy, which has been reported to be normalized if treatment is successful in controlling GH/IGF-I levels.


OBJECTIVE
Most previous studies have invariably used the last available GH/IGF-I, which may be biased as it only assesses exposure at a single point in time. We compared the last available GH/IGF-I analysis to a "time-dependent" and cumulative method, during follow-up to assess risk of mortality in the West Midlands Acromegaly study (n = 501).


RESULTS
Using the last available GH, there was a statistically significant increase in mortality comparing groups as low as GH ≤ 1 μg/L vs >1 μg/L (relative risks [RR] 1.8, P = .03). This was not the case when using the "time-dependent method," where only comparisons of GH values of GH ≤5 μg/L vs >5 μg/L were suggestive of being associated with an increased risk of mortality (RR = 1.5, P = .08). When the time-dependent GH method of analysis was used, the RR of mortality at each level was lower and the associated P value was less significant. Irrespective of using the last available or time-dependent method, when IGF-I was divided into levels according to quartile or arbitrary cutoffs, there was no significant increase in mortality with higher levels.


CONCLUSIONS
This study emphasizes the potential bias of using the latest available GH/IGF-I levels to predict mortality. Our study again highlights the limitations of IGF-I in predicting mortality.
Endocrinology, Diabetes, and Metabolism (M.S., A.A.-A., J.A., M.C.S., P.M.S.), Division of Medical Sciences, University of Birmingham, Birmingham B15 2TH, United Kingdom; Centre for Childhood Cancer Survivor Studies (R.C.R., M.M.H.), School of Health and Population Sciences, Public Health Building, University of Birmingham, Birmingham B15 2TT, United Kingdom; Department of Endocrinology (J.A.), Queen Elizabeth Hospital Birmingham, Birmingham B152TH, United Kingdom; Department of Postgraduate Medicine (R.N.C.), University of Keele, Hartshill, Stoke-on-Trent ST4 7QB, United Kingdom; Birmingham Heartlands and Solihull National Health Service Trust (A.S.B.), Birmingham B9 5SS, United Kingdom; and Department of Endocrinology and Diabetes (M.S.), Adelaide and Meath Hospitals, Incorporating the National Children's Hospital and Trinity College, Dublin, Ireland.
Mark
M
Sherlock
Raoul C
RC
Reulen
Aurora
A
Aragon-Alonso
John
J
Ayuk
Richard N
RN
Clayton
Michael C
MC
Sheppard
Michael M
MM
Hawkins
Andrew S
AS
Bates
Paul M
PM
Stewart
D000172:Acromegaly / Q000097:blood / Q000401:mortality* / Q000628:therapy; D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D005260:Female; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016896:Treatment Outcome
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I