ARTICLE
Auteur(s) : Keith D Kaufman, Jennifer
Rotonda, Arvind K Shah, Alan G Meehan
Merck Research Laboratories, 126 East Lincoln Avenue, RY34-A248,
Rahway, NJ 07065, USA
accepté le 13 Février 2008
Androgenetic alopecia (AGA; male pattern hair loss) is a common,
genetically-determined, androgen-dependent disorder, affecting
approximately 50% of men by age 40 [1, 2]. The impact of this
condition in men can be significant. Hair loss, especially in
younger men, can result in cosmetic dysphoria and lead to decreased
body-image satisfaction, increased preoccupation, stress, distress,
and a greater concern about growing older [3-8]. Moreover, fear of
suffering further visible hair loss is one of the most commonly
reported factors underlying the psychosocial distress in men with
AGA, especially in those patients seeking treatment for their
condition [5]. In spite of this, there have been no reports that
have specifically examined the effects of hair loss treatments on
the likelihood of developing further visible hair loss in men with
AGA.
Dihydrotestosterone (DHT) is the major androgen responsible for
the progressive miniaturization of scalp hair follicles and
subsequent visible hair thinning that is the hallmark
characteristic of AGA [9, 10]. Finasteride, a Type 2 5α-reductase
inhibitor, blocks conversion of testosterone to DHT [11-13].
Clinical studies have demonstrated finasteride 1 mg/day to be
an effective hair loss treatment in men with AGA [14-21]. Three
large Phase III placebo-controlled trials in men with AGA
demonstrated that treatment with finasteride 1 mg/day led to
significant improvement in scalp hair growth and appearance as well
as patient satisfaction with appearance [17-19]. Two of the three
Phase III studies with finasteride 1 mg were conducted in men
with predominantly vertex balding pattern AGA and involved an
initial 1-year, double-blind, placebo-controlled study period,
followed by four consecutive, 1-year, double-blind,
placebo-controlled extension studies [18]. These extensions
provided the unique opportunity to evaluate the effect of
finasteride 1 mg on the likelihood of further hair loss in men
with AGA over a 5-year period. Specifically, we conducted a post
hoc analysis of the effect of treatment with finasteride 1 mg
compared to placebo on the likelihood of developing further visible
hair loss based on the pooled data from a global photographic
assessment of hair growth by an expert panel of dermatologists.
Methods
Study protocols
Full methodological details for the two studies included in this
analysis have been reported previously [17, 18]. Briefly, a total
of 1553 men aged 18 to 41 with mild to moderately severe vertex
male pattern hair loss according to a modified Norwood/Hamilton
classification scale (II vertex, III vertex, IV or V) [22, 23] were
enrolled into two replicate, 1-year, double-blind, randomized
multicenter studies, which continued as four consecutive, 1-year,
double-blind, placebo-controlled, randomized extension studies.
Patients were randomized to finasteride 1 mg/day or placebo
(1:1) in the initial 1-year studies. In the four consecutive,
1-year, double-blind, placebo-controlled extension studies,
patients (N = 1215) were randomly assigned to treatment with
finasteride 1 mg/day or placebo (9: 1 during the first
extension, 9.5:1 thereafter), as determined at initial
randomization.
Assessment of scalp hair growth
The Phase III studies involved four predefined efficacy endpoints:
- 1) hair counts obtained from color macrophotographs of a
1-inch diameter circular area (5.1 cm2) of clipped
hair at the anterior leading edge of the vertex thinning area;
- 2) patient self-assessment of scalp hair using a
validated, self-administered hair growth questionnaire;
- 3) investigator assessment of scalp hair growth as
compared to baseline, using a standardized 7-point rating
scale;
- 4) global photographic assessment of scalp hair growth
in which standardized color photographs of the vertex scalp were
assessed by a panel of three expert dermatologists blinded to
treatment and experienced in photographic assessments of hair
growth, using the same standardized 7-point rating scale used for
the investigator assessment. The present analysis concerns data
derived from the fourth predefined efficacy endpoint described
above, i.e., the global photographic assessment of hair growth by a
panel of three expert dermatologists. The incidence rate of
occurrence of further visible hair loss relative to baseline, as
determined by the above global photographic assessment, is
expressed as the number of events per 100 patient-years.
Statistical analysis
The original protocol-defined data analysis plan pre-specified that
the data from the two original studies be combined in order to
improve precision of the estimates of treatment effect as well as
from the extensions due to the small size of the placebo groups in
the those studies. The protocol-defined analysis of the global
photographic assessment of hair growth involved comparison of mean
rating scores for each treatment group at each time point, based on
the 7-point rating scale, using analysis of variance. Further
exploration of the global photographic assessment data evaluated
the proportion of patients with any increase in hair growth from
baseline based on the expert panel’s assessment (categorical
analysis). Both the predefined analysis and the post hoc
categorical analysis yielded statistical significance (p < 0.001
in both analyses) between finasteride 1 mg and placebo, and
these findings have been provided previously in separate reports
[17, 18].
The present analysis assessed the effect of treatment on the
5-year likelihood of developing further visible hair loss relative
to baseline, as determined by the global photographic assessment,
using Cox proportional hazards regression analysis. Implicit in
this analysis is the assumption that the duration of follow-up,
which varied from 6 months to 5 years, was not influenced by the
development or avoidance of further visible hair loss. This
assumption was supported by the small number of discontinuations
due to lack of efficacy and the similarity of baseline
characteristics in patients who enrolled in the successive
extension studies compared to those who did not. The incidence rate
of further visible hair loss relative to baseline, as determined by
the global photographic assessment, was also calculated. Although
the two Phase III studies included two crossover groups in which
patients were switched between finasteride 1 mg and placebo
treatment during the extension phase [17, 18], the present analysis
included only the 713 patients (645 on finasteride 1 mg and 68
on placebo) who were randomized to receive either finasteride
1 mg/day or placebo throughout the initial 1-year studies and
subsequent extensions and who had global photographic assessments
during the 5-year study period. The size of the placebo cohort (N =
68) in this analysis consisted of those patients who were
randomized to receive continuous placebo treatment over 5 years,
who received at least one day of randomized placebo therapy, and
who had both baseline and at least one post-baseline global
photographic assessment, and represents slightly less than the
calculated 10% of 774 patients randomized to placebo at baseline
who were predetermined at initial randomization to continue on
placebo treatment over 5 years.
Baseline characteristics were evaluated as potential predictors
of the development of further visible hair loss. These included
baseline hair loss pattern, based on the modified Norwood-Hamilton
classification scale; duration of scalp hair loss; family history
of scalp hair loss; age at onset of scalp hair loss; and age at
randomization. The effect of these baseline factors on the
occurrence of further visible hair loss relative to baseline, as
determined by the global photographic assessment, for the
finasteride 1 mg and placebo groups, was examined.
Results
Patient accounting and baseline characteristics
A summary of the baseline characteristics for the 713 patients who
were randomized to receive either finasteride 1 mg/day or
placebo throughout the initial 1-year studies and subsequent
extensions and who had global photographic assessments during the
5-year study period is presented by treatment group in table 1. Demographics and baseline characteristics
were comparable between the two treatment groups.
Table 1 Baseline characteristics of patients with
global photographic assessments
|
Placebo
|
Finasteride 1 mg
|
|
N = 68
|
N = 645
|
|
Age (yrs; mean ± SE)
|
32 ± 0.6
|
33 ± 0.2
|
|
Age at which hair loss began (yrs; mean ± SE)
|
24 ± 0.6
|
24 ± 0.2
|
|
Duration of hair loss (yrs; mean ± SE)
|
8 ± 0.6
|
8 ± 0.2
|
|
Number (%) of patients with family history*
|
12 (18.5)
|
131 (20.7)
|
|
Number (%) of patients with hair loss pattern†
|
|
|
|
II vertex
|
11 (16.2)
|
104 (16.1)
|
|
III vertex
|
14 (20.6)
|
185 (28.7)
|
|
IV
|
21 (30.9)
|
160 (24.8)
|
|
V
|
22 (32.4)
|
196 (30.4)
|
*Family history = parents or siblings with androgenetic
alopecia.
†According to a modified Norwood-Hamilton scale.
Global photographic assessment
Based on the global photographic assessment data, treatment with
finasteride 1 mg led to a 9-fold decrease in the cumulative
incidence rate for development of further visible hair loss
(incidence rate of 3.1 versus 26.0 events/100 patient-years for
finasteride 1 mg versus placebo groups, respectively) (table 2 and figure 1). Based on the Cox
proportional hazards regression analysis of the global photographic
assessment data, finasteride 1 mg treatment led to a 93%
decrease (95% CI: 89-96%; p < 0.001) relative to placebo in the
likelihood of developing further visible hair loss over 5 years
(table 2 and figure 2). The majority
(~70%) of placebo-treated patients who remained on treatment in the
extension phase were rated by the expert panel as having developed
further visible hair loss by Year 3.
Table 2 Incidence rate and percent decrease in
likelihood of developing further visible hair loss, by subgroup
|
Patient group
|
Placebo
|
Finasteride 1 mg
|
- % Decrease in likelihood with finasteride 1 mg relative
to placebo
- (95% CI)1
|
|
N (%)
|
Incidence rate (events/100 patient yrs)
|
N (%)
|
Incidence rate (events/100 patient yrs)
|
|
All Patients
|
68 (100)
|
26.0
|
645 (100)
|
3.1
|
93% (89, 96)
|
|
Modified Norwood-Hamilton Classification
|
|
Grade II Vertex
|
11 (16)
|
16.7
|
104 (16)
|
1.3
|
95% (51, 99)
|
|
Grade III Vertex
|
14 (21)
|
25.5
|
185 (29)
|
1.7
|
95% (84, 98)
|
|
Grade IV
|
21 (31)
|
25.7
|
160 (25)
|
3.7
|
90% (77, 95)
|
|
Grade V
|
22 (32)
|
30.6
|
196 (30)
|
5.1
|
93% (83, 97)
|
- Age at onset of thinning
- Hair (yrs)
|
|
Age < 22
|
18 (27)
|
32.4
|
194 (30)
|
3.8
|
94% (85, 98)
|
|
22 ≤ Age < 26
|
25 (37)
|
26.8
|
205 (32)
|
3.0
|
94% (86, 97)
|
|
Age ≥ 26
|
19 (28)
|
18.4
|
206 (32)
|
2.2
|
91% (78, 97)
|
|
Age at randomization (yrs)
|
|
Age < 30
|
19 (28)
|
29.0
|
175 (27)
|
4.1
|
94% (83, 98)
|
|
30 ≤ Age < 36
|
26 (38)
|
26.9
|
249 (39)
|
3.1
|
93% (85, 97)
|
|
Age ≥ 36
|
23 (34)
|
23.1
|
221 (34)
|
2.6
|
93% (84, 97)
|
|
Duration of hair loss (yrs)
|
|
< 10
|
43 (63)
|
21.8
|
425 (66)
|
3.1
|
92% (84, 96)
|
|
10 to 24
|
19 (28)
|
33.3
|
180 (28)
|
2.8
|
96% (90, 98)
|
|
Parents’ history of hair loss
|
|
Yes
|
45 (66)
|
27.9
|
440 (68)
|
3.2
|
94% (89, 97)
|
|
No
|
20 (29)
|
20.0
|
187 (29)
|
3.0
|
91% (77, 97)
|
- Grandparents’ History of
- Hair Loss
|
|
Yes
|
43 (63)
|
27.2
|
401 (62)
|
3.4
|
93% (88, 96)
|
|
No
|
10 (15)
|
27.9
|
157 (24)
|
2.5
|
95% (84, 99)
|
1Based on Cox proportional hazards regression
analysis.
Subgroup analyses
Modified Norwood-Hamilton classification at baseline: Among
placebo-treated patients, the incidence rate for development of
further visible hair loss was greater in men with a more severe
hair loss pattern (higher modified Norwood-Hamilton classification)
at baseline compared with men with a less severe baseline hair loss
pattern classification (incidence rate of 30.6 versus 16.7
events/100 patient-years in placebo-treated men with a baseline
classification of grade V versus grade II vertex, respectively;
table 2 and figure 3A). Regardless,
treatment with finasteride 1 mg led to a consistent decrease
(90-95% decrease in likelihood) relative to placebo in the 5-year
likelihood of developing further visible hair loss across the four
subgroups defined by their baseline hair loss pattern (table 2).
Duration of hair loss
Among placebo-treated patients, the incidence rate for development
of further visible hair loss was greater in men with a duration of
hair loss of 10 to 24 years compared with men having a duration of
hair loss < 10 years (33.3 versus 21.8 events/100 patient-years;
table 2 and figure 3B). Treatment with
finasteride 1 mg led to a consistent decrease (92-96% decrease
in likelihood) relative to placebo in the 5-year likelihood of
developing further visible hair loss in the two subgroups defined
by duration of hair loss (table 2).
Family history of hair loss
In placebo-treated patients, the incidence rate for development of
further visible hair loss was greater in men with a parental
history of hair loss compared with men with no parental history of
hair loss (27.9 versus 20.0 events/100 patient-years; table 2 and figure 3C). In contrast,
placebo-treated patients with a second degree family history of
hair loss (i.e., positive history of hair loss in either
grandparent) showed no difference in the incidence rate for
development of further visible hair loss compared with men with no
second degree family history of hair loss (27.9 versus 27.2
events/100 patient-years; table 2 and
figure 3D).
Treatment with finasteride 1 mg led to a consistent decrease
(91-95% decrease in likelihood) relative to placebo in the 5-year
likelihood of developing further visible hair loss in the four
subgroups defined by family history of hair loss (table 2).
Age at onset of thinning hair
Among placebo-treated patients, the incidence rate for development
of further visible hair loss was greater in men whose onset of
scalp hair loss occurred at a younger age compared with men whose
onset of thinning hair occurred at an older age (incidence rate of
32.4 versus 18.4 events/100 patient-years in men whose onset of
thinning hair occurred at age < 22 years compared with men whose
onset of thinning hair occurred at age ≥ 26, respectively) (table 2 and figure 3E). Treatment with
finasteride 1 mg led to a consistent decrease (91-94% decrease
in likelihood) relative to placebo in the 5-year likelihood of
developing further visible hair loss across the three subgroups,
defined by the age of onset of scalp hair loss (table 2).
Age at randomization
Among placebo-treated patients, the incidence rate for development
of further visible hair loss was greater in younger men compared
with older men (29.0 versus 23.1 events/100 patient-years in men
randomized at age < 30 years versus men ≥ 36 years,
respectively) (table 2 and figure 3F). Treatment with
finasteride 1 mg led to a consistent decrease (93-94% decrease
in likelihood) relative to placebo in the 5-year likelihood of
developing further visible hair loss across the three ages at
randomization cohorts (table 2). Figure 4 shows typical
vertex scalp global photographs at baseline and Year 5 for two
young men, one on placebo (panels A and B; patient enrolled at age
29 years) and the other on finasteride 1 mg (panels C and D;
patient enrolled at age 19 years). By Year 5, the placebo patient
was assessed by the expert panel as having developed moderately
decreased hair growth relative to baseline (figure 4B), whereas the
finasteride 1 mg patient was assessed as having no change in
hair growth (figure
4D).
Discussion
The data from the two Phase III studies included in this analysis
represent the longest reported placebo-controlled observations of
the development of further visible hair loss in men with AGA. To
date, no other blinded, placebo-controlled studies in men with AGA
have been of sufficient duration to allow for an analysis of the
effect of pharmacological treatment on the likelihood of developing
further visible hair loss. The present analysis of global
photographic assessment data from these studies demonstrated that
treatment with finasteride 1 mg led to a significant and
durable decrease in the likelihood of developing further visible
hair loss in men with AGA over 5 years.
In the course of this analysis, 5 risk factors were identified
as being positively correlated with more rapid progression of
further visible hair loss: increased duration of hair loss at
baseline, family history of hair loss at baseline, severity of the
hair loss pattern at baseline, younger age at onset of hair loss,
and younger age at randomization. These findings suggest that there
may be differences among men with AGA with respect to the
susceptibility of scalp hair follicles to miniaturize and the rate
at which progressive visible hair loss occurs.
The efficacy of finasteride 1 mg relative to placebo was
evident within 6 months of starting therapy, with the decrease in
likelihood being sustained throughout the 5-year study period. In
contrast, the likelihood of developing further visible hair loss in
the placebo group progressively increased over 5 years. The percent
of patients developing further visible hair loss in the placebo
group versus the finasteride group, respectively, was 13% versus 1%
at one year, 69% versus 9% at 3 years, and 75% versus 10% at 5
years for those patients remaining on treatment in the extension
phase, consistent with continuing scalp hair follicle
miniaturization and the subsequent progression of visible hair loss
that characterizes AGA.
This analysis provides strong evidence that there is age-related
variability among men with AGA with respect to their sensitivity to
the mechanism(s) that trigger the onset and rate of progression of
visible hair loss, with higher rates of occurrence of further
visible hair loss being seen in younger placebo-treated men and in
men whose onset of hair thinning occurred at a young age (late
teens/early 20s). These findings are in agreement with that of a
previous study in men with early-onset AGA [24]. In that study,
there was a rapid rate of hair loss observed in patients who
started losing their hair in their late teens or early 20s, such
that by age 30 or earlier they exhibited severe hair loss of the
Norwood-Hamilton pattern VI or VII. The present findings also
provide a basis for the higher level of distress expressed by
younger men with AGA, who show the greatest level of worry that
their hair loss will worsen and are more likely to seek treatment
for their condition [5, 6]. Thus, the clinical basis for this
concern seems well founded in light of the finding that younger men
and men who started losing their hair at a relatively young age had
higher rates of occurrence of further visible hair loss.
The increased rate of occurrence of further visible hair loss in
placebo-treated men with a first degree family history of hair loss
is in agreement with the genetically-determined predisposition to
develop AGA [1]. In contrast, we did not observe a similar
relationship based on second degree family history of hair loss.
The apparent difference between the influence of first versus
second degree family history of hair loss may be reflective of the
presumed polygenic nature of AGA, which could conceivably lead to a
weak multi-generational expression of the phenotype for this
condition.
Importantly, regardless of the subgroup or the overall level of
future likelihood of developing further visible hair loss,
treatment with finasteride 1 mg conferred a similar level of
decrease in this likelihood (≥ 90% relative to placebo in all
subgroups). This finding supports the view that DHT, formed by the
action of Type 2 5α-reductase, plays an important role in mediating
progressive scalp hair loss in men with AGA, irrespective of their
baseline characteristics.
Previous reports from the two Phase III vertex hair loss studies
demonstrated finasteride 1 mg to have an excellent safety
profile in men with AGA [17, 18]. Only 1.2% of men receiving
finasteride 1 mg discontinued treatment due to these adverse
experiences (compared with 0.9% of men in the placebo group) with
resolution occurring after discontinuation of drug. The most
commonly reported drug-related adverse experiences in these studies
were sexual adverse experiences, which were reported at an
incidence of < 2% in men receiving finasteride 1 mg during
the first year of treatment (decreased libido, reported by 1.8% of
men on finasteride 1 mg vs. 1.3% on placebo; erectile
dysfunction, 1.3% with finasteride 1 mg vs. 0.7% with placebo;
and ejaculation disorder, 1.2% with finasteride 1 mg vs. 0.7%
with placebo). The incidence of each of the above adverse
experiences decreased to ≤ 0.3% by the fifth year of treatment with
finasteride 1 mg. No other significant drug-related adverse
events were reported in these clinical studies.
In summary, although AGA in men is a progressive disease [25],
treatment with finasteride 1 mg will decrease the likelihood
of further visible hair loss. The key role of DHT in mediating
progressive scalp hair loss in men with AGA is reinforced by the
marked decrease in the likelihood of visible hair loss in
finasteride 1 mg-treated patients relative to placebo,
regardless of the subgroup examined. When treated with finasteride
1 mg, certain subgroups, particularly those separating patient
age, age at onset of hair loss, extent of hair loss, duration of
hair loss, and first degree family history of hair loss, had a
smaller decrease in the rate of further visible hair loss during a
5-year period of observation, suggesting that there are differences
among men with AGA with respect to the degree of susceptibility of
scalp hair follicles to continued follicular miniaturization.
Acknowledgements
This study was funded by Merck Research Laboratories, Merck &
Co., Inc., the company that manufactures and markets finasteride.
The authors wish to acknowledge the technical assistance of Mr.
Douglas Canfield, of Canfield Scientific, Inc., in the development
of photographic procedures used in these clinical studies. We are
also grateful to Dr. Amy O. Johnson-Levonas for her assistance with
this manuscript. This study was supported by a grant from Merck
& Co., Inc. Keith D. Kaufman, Jennifer Rotonda, Arvind K. Shah,
and Alan G. Meehan are employees of and hold stock in Merck &
Co., Inc.
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