mellitus with (14%) or without (0%) insulin depen-
dence.
Other
concomitant
conditions
included
current cigarette smoking (3%), a history of cigarette
smoking (21%), occasional to moderate alcohol
consumption (49%), depression (6%), erectile dys-
function before radical prostatectomy (29%) and
testosterone replacement therapy before radical
prostatectomy (3%). The most common Gleason
score was 3
þ
3 in 33 of 58 patients with patho-
logy results available (Gleason score range 3
þ
3
to 4
þ
5).
To assess whether validated questionnaires for
self-reporting of sexual function correlate with IGF-1
levels, serum IGF-1 levels were correlated with
SHIM questionnaire scores. The median
±
s.d. serum
IGF-1 level across the subject pool was 235.0
±
86.4 ng dl
±
1
(range 87–506 ng dl
±
1
) (Table 1). The
median
±
s.d. SHIM questionnaire score was 19.0
±
8.7 (range 1–25). After the data distribution had
been determined to be non-parametric using histo-
gram analysis, Spearman’s rank correlation coeffi-
cients were calculated between IGF-1 and SHIM
scores. There was a significant correlation between
IGF-1 levels and total SHIM scores for all ages
(
r
¼
0.31
P
¼
0.02) (Table 2, Figure 1). Notably, there
was also a significant correlation between IGF-1
level and score for each individual SHIM question
for all ages (Table 2, SHIM 1—SHIM 5). Stratifica-
tion based on subject age demonstrated a significant
correlation between IGF-1 level and SHIM score in
men
4
70 years old for total SHIM score (
r
¼
0.89,
P
¼
0.04) and all individual questions (Table 2). In
contrast, no significant correlation was demon-
strated between IGF-1 level and total SHIM score
for any other age group, although a correlation
approaching statistical significance was observed
in the 50–59-year-old age group for total SHIM score
(
r
¼
0.32,
P
¼
0.08), a significant correlation was
observed for the second SHIM question (SHIM 2,
r
¼
0.41,
P
¼
0.02) in this age group. Although it is
unclear why no statistically significant correlation
between questionnaire scores and IGF-1 levels in
younger age groups is observed, there are no signi-
ficant differences in IGF-1 levels between age
groups, while EPIC and SHIM scores were relatively
higher in younger men, which may affect the corre-
lation between IGF-1 levels and questionnaire
scores in these age groups. Taken together, these
data suggest that the
4
70-year-old age group is the
most sensitive demographic to assess using the
SHIM questionnaire if aiming to determine whether
sexual function is related to IGF-1 levels, although
the SHIM score may also be predictive in other
age groups based on the isolated finding in the 50–
59-year-old group. In addition, we should also
consider the possibility that the statistically signi-
ficant differences observed in our subgroups could
result
simply
from
chance.
Larger
population
studies may better clarify the age-specific utility of
IGF-1 levels as a predictor of sexual function.
Subjects’ IGF-1 levels were also correlated with
self-reported sexual function as assessed using the
sexual and hormonal domains of the EPIC ques-
tionnaire. The median
±
s.d. score of the sexual
domain of the EPIC questionnaire was 56.4
±
28.3
(range 6.3–96.2) (Table 1). Similar to the findings
with SHIM score, there was a significant correlation
between the sexual domain of the EPIC question-
naire and IGF-1 levels for all ages (
r
¼
0.30,
P
¼
0.02)
Table 2
Spearman’s correlation coefficients between IGF-1 and
SHIM/EPIC scores, IGF-1 and testosterone, by age
Age group
IGF-1 vs
RP
-value
All ages
Total SHIM
0.31
0.02
SHIM 1
0.33
0.01
SHIM 2
0.30
0.02
SHIM 3
0.28
0.03
SHIM 4
0.26
0.04
SHIM 5
0.25
0.05
EPIC sex
0.30
0.02
EPIC horm
±
0.16
0.21
Testosterone
±
0.03
0.84
4
70 years
Total SHIM
0.89
0.04
SHIM 1
0.74
0.15
SHIM 2
0.95
0.01
SHIM 3
0.95
0.01
SHIM 4
0.94
0.02
SHIM 5
0.97
0.01
epic sex
0.87
0.06
EPIC horm
0.46
0.43
Testosterone
0.56
0.20
60–69 years
Total SHIM
0.26
0.26
SHIM 1
0.41
0.07
SHIM 2
0.10
0.66
SHIM 3
0.18
0.43
SHIM 4
0.18
0.43
SHIM 5
0.17
0.47
EPIC sex
0.19
0.41
EPIC horm
±
0.29
0.20
Testosterone
0.12
0.59
50–59 years
Total SHIM
0.33
0.09
SHIM 1
0.31
0.10
SHIM 2
0.41
0.02
SHIM 3
0.29
0.12
SHIM 4
0.23
0.22
SHIM 5
0.22
0.24
EPIC sex
0.32
0.08
EPIC horm
±
0.20
0.30
Testosterone
±
0.21
0.26
40–49 years
Total SHIM
±
0.74
0.26
SHIM 1
±
0.89
0.11
SHIM 2
NA
NA
SHIM 3
±
0.26
0.74
SHIM 4
NA
NA
SHIM 5
NA
NA
EPIC sex
0.32
0.68
EPIC horm
0.40
0.60
Testosterone
0.40
0.60
Abbreviations: IGF-1, insulin-like growth factor 1; EPIC, Ex-
panded Prostate Cancer Index Composite; SHIM, Sexual Health
Inventory for Men.
‘R’ represents the Spearman’s correlation coefficient. ‘EPIC sex’
refers to the sexual domain portion of the EPIC questionnaire,
whereas ‘EPIC horm’ refers to the hormonal domain. SHIM 1—
SHIM 5 refer to individual questions of the SHIM questionnaire.
IGF-1 levels correlate with sexual dysfunction
AW Pastuszak
et al
222
International Journal of Impotence Research