Improved prediction of all-cause mortality by a combination of serum total testosterone and insulin-like growth factor I in adult men.
OBJECTIVE
Lower levels of anabolic hormones in older age are well documented. Several studies suggested that low insulin-like growth factor I (IGF-I) or testosterone levels were related to increased mortality. The aim of the present study was to investigate the combined influence of low IGF-I and low testosterone on all-cause mortality in men.


RESULTS
From two German prospective cohort studies, the DETECT study and SHIP, 3942 men were available for analyses. During 21,838 person-years of follow-up, 8.4% (n=330) of men died. Cox model analyses with age as timescale and adjusted for potential confounders revealed that men with levels below the 10th percentile of at least one hormone [hazard ratio (HR) 1.38 (95% confidence-interval (CI) 1.06-1.78), p=0.02] and two hormones [HR 2.88 (95% CI 1.32-6.29), p<0.01] showed a higher risk of all-cause mortality compared to men with non-low hormones. The associations became non-significant by using the 20th percentile as cut-off showing that the specificity increased with lower cut-offs for decreased hormone levels. The inclusion of both IGF-I and total testosterone in a mortality prediction model with common risk factors resulted in a significant integrated discrimination improvement of 0.5% (95% CI 0.3-0.7%, p=0.03).


CONCLUSIONS
Our results prove that multiple anabolic deficiencies have a higher impact on mortality than a single anabolic deficiency and suggest that assessment of more than one anabolic hormone as a biomarker improve the prediction of all-cause mortality.
Institute of Clinical Chemistry and Laboratory Medicine, Ernst Moritz Arndt University, Greifswald, Germany. nele.friedrich@uni-greifswald.de
Nele
N
Friedrich
Harald J
HJ
Schneider
Robin
R
Haring
Matthias
M
Nauck
Henry
H
Völzke
Heyo K
HK
Kroemer
Marcus
M
Dörr
Jens
J
Klotsche
Caroline
C
Jung-Sievers
David
D
Pittrow
Hendrik
H
Lehnert
Winfried
W
März
Lars
L
Pieper
Hans-Ulrich
HU
Wittchen
Henri
H
Wallaschofski
Günter K
GK
Stalla
D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood*; D005500:Follow-Up Studies; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000172:deficiency; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000208:ethnology; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D013739:Testosterone / Q000097:blood* / Q000172:deficiency
D013739:Testosterone; D007334:Insulin-Like Growth Factor I