Current Measures for the Evaluation of Acne Severity
Abstract and Introduction
Abstract
The overall assessment of acne severity requires consideration of both
clinical measures and patient-reported outcomes. This review is focused on
recent developments in these interrelated spheres of severity determination.
There are multiple current grading scales for active acne and scarring.
Furthermore, a number of acne-specific quality-of-life (QoL) measures have been
developed. Selection of the most appropriate measures for acne severity is
dependent on the intended application. For therapeutic investigations projected
for regulatory approval, lesion counting, negotiated and approved global acne
scales and complete QoL instruments are advisable. In clinical practice,
however, global assessments and indices of QoL instruments may be more
practical.
Introduction
Acne is a common skin disorder afflicting more than 85% of adolescents
[1] and can
persist or develop over time to affect up to 50% of adults older than 20 years
of age. Although the prevalence of acne and severity generally improves with
time, worsening was reported by 4% of men and 13% of women.
[2] The
largest population-based survey of acne involved 105 dermatology residents and
just over 20,000 noninstitutionalized people in the USA.
[3]
This study generated an overall US population acne prevalence estimate of 13%.
Of the patients with acne, 17% were younger than 15 years, while 81% were aged
15-44 years. Furthermore, the latter age range accounted for 96% of those with
severe acne. In this age group, 71% had no acne, while 19% had mild, 9% had
moderate and 1% had severe acne. Thus, of those with acne, approximately a
third had moderate-to-severe involvement. Overall, males tended to have a
higher prevalence and severity of acne than females. In the USA, acne is the
single most common diagnosis for dermatologist visits for people aged from 14
to 45 years.
[4]
Substantial healthcare resources and consumer expenditures are committed to the
treatment of acne. In 2002, the total cost burden of acne and its treatment was
estimated to exceed US$1 billion annually.
In 2002, the most comprehensive review of acne research literature was
undertaken by the Agency for Healthcare Research and Quality.
[5] In
this systematic structured review of acne therapy, 4749 acne trials were
initially identified by computerized database searches. Articles were
subsequently excluded if they did not address treatment, did not include data
in humans, addressed conditions other than acne vulgaris, were not original
research, were not published in English or were duplicate publications. This
exclusion process resulted in 274 trials being selected for further analysis.
The lack of standardization in severity reporting was a primary shortcoming
identified by this review. The most frequently cited grading systems were based
on comparison with photographic standards, text descriptions or lesion counts
of the entire face or a portion thereof. As expert advisors of this project had
identified acne severity as the most important patient characteristic in
treatment profiling, an attempt to standardize these disparate measures was
undertaken. The Combined Acne Severity Classification was developed as a tool
to assist in further analysis and was not proffered as a scale for severity
assessment in future research. This scale comprised three categories:
- Mild acne:
fewer than 20 comedones, or fewer than 15 inflammatory lesions or a total
lesion count lower than 30;
- Moderate
acne: 20-100 comedones, or 15-50 inflammatory lesions or a total lesion
count of 30-125;
- Severe
acne: more than 5 cysts, or comedone count greater than 100, or a total
inflammatory count greater than 50, or a total lesion count greater than
125.
The methodological conclusions of this review were that the acne literature
was heterogeneous at multiple levels, including acne severity, outcome
assessments and comparison. In assessing disease severity, they further
recommended explicit and standard methods of lesion counting, severity ratings
and psychometric measurements.
The clinical presentation of active acne varies extensively owing to the
multiple features of disease, including primary lesional types, numbers and
distribution, density, extent and regions of involvement. When these are
combined with similar considerations for secondary lesions, it is evident that
grading acne severity is a complex undertaking. In clinical medicine, the
primary rationale for determining severity is to guide the selection of the
most appropriate therapy. The objectives of acne treatment are to clear and
prevent active lesions, reduce the risk of scarring and minimize psychosocial
impact. Beyond individual patient care, however, severity determination is an
important aspect of basic, clinical and epidemiologic research. In dermatology,
while cutaneous examination has largely been the primary basis for severity
evaluation, increasing recognition of the intangible consequences of skin
disease has led to the development of psychometric instruments. Such measures
provide information relevant to the impact of skin disease on social,
psychological and other dimensions relevant to the quality of life (QOL) of
patients. Inclusion of patient-reported outcomes on the impact of acne provides
an additional dimension to understanding the burden of disease.
Despite numerous systems for the classification of acne severity, there is
no universal standard.
[5,6]
The American Academy of Dermatology sponsored Consensus Conference on Acne
Classification in 1991 concluded that a strictly quantitative definition of
acne severity was not feasible owing to the variable expression of acne
features and that acne severity grading be most effectively accomplished by
means of a pattern-diagnosis or a global evaluation system.
[7]
This system was to be based on consideration of lesional type and extent
(specifically, extensive papulopustular disease and persistent or recurrent
nodules), ongoing scarring, persistent drainage from lesions, sinus tracts,
adverse psychosocial impact and recalcitrance to therapy.
The purpose of this review is to update developments in outcome measures of
acne severity relevant to clinicians, clinical investigators and regulatory
authorities. In particular, the focus is on the measures of acne severity that
may be practical for use in the clinic and investigational trials, and which address
the elements expounded by the consensus group - specifically regarding the
issues of active acne focusing on primary lesions, the extent of acne scarring
and psychosocial impact.
Morphological Features of Acne
Lesional types in acne vulgaris may be divided into those that are primary
or secondary. Primary lesions are characteristic for active acne, while
secondary lesions represent their sequelae or consequence.
Primary Lesions
Primary acne lesions are further divided into those that are noninflammatory
(comedones) and inflammatory (papules, pustules, nodules and cysts).
Noninflammatory lesions are solid small pale papules, typically with a diameter
of less than 1 mm, containing a core of white debris comprised of sebum and
keratotic debris (closed comedones) or a dark-gray core of debris due to
exposure to air and subsequent oxidation (open comedones). Inflammatory lesions
range from elevated solid erythematous papules, pustules containing a core of
purulent material, to larger indurated lesions. The latter are designated as
nodules if they are at least 5 mm in diameter. Some lesions may become
fluctuant, leading to cysts. After rupture, some of these may result in deep
scars and sinus tracts.
Secondary Lesions
Secondary lesions develop as a consequence of primary lesions or the
manipulation thereof. They are not, however, specific for the underlying
disease process. In acne, secondary features resulting from resolution of
primary lesions include postinflammatory erythema, hyperpigmentation and
scarring. The manipulation of primary acne lesions by patients can lead to
excoriations and consequential scarring.
Methods of Grading Acne Severity
Evaluation of acne severity has been undertaken from two polar perspectives:
elemental or reductionistic (in which severity is based upon the quantification
of specific lesion types); and holistic (in which the gestalt of entire
presentation is considered and then categorized based on a pre-established
repertoire of severity presentations). Recognition of the complexities in
severity determination of acne has led the US FDA to recommend using both as
coprimary end points.
[8]
They acknowledge that lesion counts alone may be inaccurate owing to the
exclusion of other factors associated with the pleiomorphic nature of acne.
Furthermore, the disadvantages of lesion counting include a lower precision in
actual evaluation studies and impracticality in the clinical setting. In the
vernacular of the regulatory research paradigm, the Investigator's Global
Assessment (IGA) is the physician's overall or global assessment of the
condition. To maintain the gestalt of this measure, which accounts for
admixture of lesion types, their quality and quantity and the extent and
density of involvement (numerical ranges for lesion types) were discouraged.
Acne Lesion Counting
Acne lesion counting was first published as a measure of acne severity in
1966 in the conduct of a clinical drug trial.
[9]
It has since endured as a primary outcome measure of severity in clinical
research studies. In this application, the specificity of counting is valuable,
as acne treatments may have a greater effect on certain lesion types. The
decisional process in counting specific lesions is binary and provides a
continuous set of variables particularly suited to statistical testing and the
research paradigm.
In the counting procedure, primary acne lesions are evaluated and accounted
for independently: comedones, papules/pustules and nodules/cysts. Demarcation
zones for the face extend from the anterior hairline (or approximation thereof
with balding) to the temporal fringe and along the preauricular sulcus to the
jawline and chin. In addition to proper lighting, patient positioning and prior
facial skin preparation (removal of makeup for women, gentle shaving to
minimize irritation for men), the use of a facial template to organize facial
regions into sectors, such as the forehead, each cheek, nose and perioral
region, may be helpful. While palpation of lesions is allowed - for example, to
discriminate between macular erythema from inflammatory papules - magnification
is not.
Theoretical limitations in lesion counting as an index of overall acne
severity include the complexity in accounting for the interplay between
different lesion types, numbers, distribution and density. In particular, the
clinical relevance to overall severity of varying lesion types and counts are
inadequately defined. Such a determination would require the ability to study
the effect of simultaneous changes in both type and number of lesions. Despite
the apparent simplicity and objectivity of lesion counting, judgment and
subjectivity are frequently necessary.
[10]
Finally, the time required to conduct lesion counts decreases practicality and
the likelihood of uptake in usual clinical practice.
The reliability of lesion counting has been evaluated in two previous
studies. In a study involving 12 raters (three physicians and nine nurses) and
12 acne subjects, intralass correlation coefficients (ICCs) were used as a
measure of rater reliability. ICC values approximating 1.0 indicated excellent
reliability, while values less than 0.75 were considered less precise.
[11]
Inter-rater reliability estimates were 0.52 for comedone counts and 0.76 for
inflammatory papule/pustule counts. However, intra-rater ICCs ranged from 0.74
to 0.98 for comedone counts and 0.73 to 0.98 for papule/pustule counts.
[12]
Thus, lesion counts were more reliable if conducted by the same rater.
A more recent study involving 11 dermatologists and six acne subjects
corroborated these findings.
[13]
In this study, the raters were separated into two groups to determine the
effect of a formal training session on lesion counting and acne-severity
grading. One group was trained prior to the first of two subject-evaluation
sessions, while the second group was trained only after the first
subject-evaluation session. The group trained prior to subject evaluations
demonstrated inter-rater reliability estimates of 0.68 and 0.72 for
noninflammatory and inflammatory lesions, respectively. Corresponding mean intra-rater
reliability estimates were 0.83 and 0.79. The training sessions improved
inter-rater reliability in noninflammatory counts and increased the proportion
of raters with good reliability (ICC ≥ 0.75) in all three outcome measures
(including global assessments). Practice also improved reliability in all three
outcome measures. Thus, training dermatologists has a demonstrable effect on
reliability of lesion counting, as does practice.
Acne Global Assessment Scales
Global assessment scales assimilate the totality of the clinical
presentation into a single category of severity. Severity categories are
established upon a prior experiential repertoire, based on photographic or
descriptive text. Global methods are particularly suited to clinical practice
owing to their practicality. In clinical investigations, global assessments are
a coprimary end point of efficacy as they are considered to be of greater
clinical relevance than lesion counts alone.
The prerequisites of an ideal global acne scale include a restricted number
of categories, sufficient detail in descriptions to reduce observer
variability, relevance of severity levels for treatment selection, static
measurements with no reference to a prior level of severity, universality for
use in practice and investigations, correlation with lesion counts
[14]
responsivity to change, comprehensiveness for common areas of involvement, such
as the face, chest and back, and practicality.
[15]
Despite the availability of more than 25 grading systems for acne,
[6]
the lack of a single, standardized system consistently used in practice and
research reflects their inability to fulfill these attributes. While an
historical account of earlier acne grading scales has been published elsewhere,
[16]
the current focus is on global grading systems developed since the consensus
conference in 1991 (
Table
1 ). A classification proposal developing from this conference was a
three-category system for inflammatory acne, where mild was comprised of few to
several papules/pustules; moderate of several to many papules/pustules and few
to several nodules; and severe of numerous or extensive papules/pustules and
many nodules.
[7]
Noninflammatory lesions did not comprise this scale, nor was a separate scale
for such lesions provided. No specific directives were provided in the
application of this scale to the face, chest and back, or whether it was to be
applied in the aggregate to all these regions.
The Leeds Revised Acne Grading System, published in 1998, provides a
photographic standard for acne grading of the face, back and chest.
[17]
This system is comprised of 15 facial grades (three solely for comedonal acne)
and eight each for the chest and back. These representations were selected from
over 1000 photographs by an expert panel of three dermatologists and four acne
assessors. The photographs were ranked on four further occasions as a means of
content validation by the authors. The varying representations of severity and
the large number of categories within each region, however, make this system
cumbersome to apply in clinical practice. Furthermore, this system does not
adequately differentiate those with the lowest acne grades, while categories of
extreme acne severity are over-represented.
[15]
The Global Acne Grading System (GAGS) is a quantitative scoring system in
which the total severity score is derived from summation of six regional
subscores.
[18]
Each is derived by multiplying the factor for each region (factor for forehead
and each cheek is 2, chin and nose is 1 and chest and upper back is 3) by the
most heavily weighted lesion within each region (1 for ≥ one comedone, 2 for ≥
one papule, 3 for ≥ one pustule and 4 for ≥ one nodule). The regional factors
were derived from consideration of surface area, distribution and density of
pilosebaceous units. As yet, this system has not been validated against other
global scales or lesion counts, nor evaluated for reliability.
The grading scale for overall severity by Allen and Smith Jr has been the
template for global assessments in many acne trials as an Investigators' Global
Assessment (IGA) scale. They provided text descriptions of five categories but
allowed for nine acne grades similar to the scale of Cook
et al., who
also included photographic standards.
[11]
The system proposed by Allen and Smith Jr, however, was based solely on
descriptive text, not on photographs, and also added the dimension of
increasing extent of facial involvement. They further demonstrated that the
severity scale correlated with inflammatory and noninflammatory lesion counts.
[19]
Although limited to facial acne, this system has subsequently been expanded for
application to acne on the chest and back.
[15]
Demarcation zones for the chest were the suprasternal notch laterally to
shoulders superiorly and the level of the xiphoid process inferiorly; while the
back was demarcated by the base of the neck, laterally to shoulders and
inferiorly by the costal margin. Each of these regions was then individually
graded for acne with the categorical grading scale. A high level of correlation
was demonstrated compared with the Leeds Revised Acne Grading System. Comparing
both systems at all three sites, acne graded by the global system approximated
a normal distribution and more definitively distinguished the clear/almost
clear from mild categories. This is a critical issue in defining treatment
success in clinical treatment trials. The reliability of this system as applied
to facial acne has been demonstrated previously in which trained dermatologists
demonstrated inter-rater reliability estimates of 0.65 in the first patient
evaluation session and 0.77 for the second.
[13]
A similar six-category global scale was found to be more reliable than other
global scales including the three-category scale proposed by the consensus
conference and the Leeds scale.
[12]
This validated system fulfills many of the attributes recommended for an ideal
global system, including a restricted number of categories to facilitate
practicality, static evaluations, comprehensiveness to enhance content
validity, reliability, practicality and universality with prior inclusion as an
outcome measure in clinical drug trials.
A recent proposal by the US FDA for a five-category global system may
provide even greater reliability as the descriptive text is more explicit.
[8]
In this scale, the five categories ranged from:
- Clear,
indicating no inflammatory or noninflammatory lesions;
- Almost
clear, rare noninflammatory lesions with no more than one papules/pustule;
- Mild, some
noninflammatory lesions, no more than a few papules/pustules but no
nodules;
- Moderate,
up to many noninflammatory lesions, may have some inflammatory lesions,
but no more than one small nodule;
- Severe, up
to many noninflammatory and inflammatory lesions, but no more than a few
nodules.
A recent study established a global facial acne severity scale (mild,
moderate, severe and very severe) by use of intuitive (categories not
specifically predefined) severity grades.
[20]
Dermatologists initially graded half-face severity of 244 acne patients and
also counted lesions. Their judgments on severity grades were then compared
with those of an expert panel of three dermatologists who evaluated half-face
photographs of the same patients. Concordance of severity judgments between the
initial rater and the entire panel of three raters was 45%, while concordance
with at least two panel raters was 69%. Correlation of severity grades with
lesion counts was highest for inflammatory papules and pustules but not for
comedones, nodules or cysts. In those cases for which severity grading was
unanimous, correlation with the numerical range of inflammatory papule and
pustules was determined and then evaluated to provide a clear delineation of categories.
Classification of acne severity based on inflammatory papule/pustule counts on
half-face evaluation was determined to be 0-5 for mild, 6-20 for moderate,
21-50 for severe and more than 50 for very severe. Finally, half-face
photographs from the consensus grading were selected to visually represent the
four severity grades.
Methods for Grading Acne Scars
Formal evaluation of the incidence of acne scarring in the context of acne
severity and lesion type was first initiated by Layton
et
al. [21]
In a hospital referral clinic setting, the overall prevalence of acne scarring
was 95%. The incidence of facial scarring was greater than the back or chest.
Of the atrophic varieties, ice-pick scars were most frequent on the face, as
were macular atrophic scars. However, follicular macular atrophic scars were
most frequently observed on the torso. Hypertrophic/keloidal scarring was seen
most frequently on male trunks. Acne scarring scores were significantly higher
in males at all sites for each initial Leeds acne score. The duration of acne
untreated for up to 3 years correlated significantly with progressively higher
scar scores at the face and trunk. Beyond this time, no further increase in
scar scores was observed. While 85% of those with hypertrophic/keloidal scars
had suffered from nodular inflammatory acne at some period in the course of
their disease, 15% had reported only superficial inflammatory lesions.
These findings emphasize the importance of acne scar severity determination
in the context of acne-severity grading, as ongoing scarring is representative
of greater severity.
[7]
Thus, a measure of acne scarring should be an important component of
acne-severity evaluations. However, while various scar scales have been
published, none were developed to be used in conjunction with measures of
active acne. Currently available acne scarring-severity scales are shown in (
Table 2 ).
In the study by Layton
et al. conducted at the Leeds
General Infirmary,
[21] the
severity of acne scarring was evaluated by lesion counts of atrophic and
hypertrophic/keloidal scars. Atrophic scars - defined morphologically as
ice-pick, macular atrophic or follicular macular atrophic - these translated
into scores ranging from 1 to 6 representing 1-5, 6-10, 11-25, 26-50, 51-100 and
more than 100 scars, respectively. Ice-pick scars were described as those with
an irregular border, jagged edges and sharp margins with steep sides leading to
a fibrotic base. Macular atrophic scars were soft and distensible in which the
base was often easily creased. Follicular macular atrophic scars were described
as small white perifollicular papules or macules. The authors separately
quantified keloidal and hypertrophic scars owing to their greater level of
disfigurement. Score allocation of 2, 4 and 6 represented one to three, four to
seven and more than seven scars of this type, respectively. Keloidal scars were
described as those that were indurated and extending beyond the boundaries of
the initiating inflammatory acne lesion, while hypertrophic scars were defined
as less raised and conforming to the area of the primary acne lesion. A total
scar score was then obtained by adding the scores from both atrophic and
hypertrophic categories. Such total scores could be calculated separately for
the face, chest and back to provide a comprehensive system for scar evaluation.
A potential limitation of this system is the time required for calculation of
the relevant scar scores.
The ECCA (Echelle d'Evaluation clinique des Cicatrices d'acné) for facial
acne scarring is based on summation of individual types of scars and their
numerical extent.
[22]
Scar types considered to be more visibly disfiguring were accorded greater
severity weights. Specific scar types and associated weighting factors were the
following:
- Atrophic
scars with diameter less than 2 mm: 15
- U-shaped
atrophic scars with a diameter of 2-4 mm: 20
- M-shaped
atrophic scars with diameter greater than 4 mm: 25
- Superficial
elastolysis: 30
- Hypertrophic
scars with a less than 2-year duration: 40
- Hypertrophic
scars of greater than 2-year duration: 50
A semi-quantitative assessment of number of each of these scar types was
then determined with a four-point scale, in which 0 indicates no scars, 1 indicates
less than five scars, 2 indicates between five and 20 scars and 3 indicates
more than 20 scars. In this manner, the relative extent of scarring for each
scar type was calculated. The summation scores for all six scar types then
comprised the global scar score, which could vary from 0 to 540. In a study on
the reliability of this scale, seven dermatologists underwent a 30-min training
session prior to the evaluation of ten acne patients. There was no statistical
difference in score grading between participating dermatologists. The global
scores, however, varied from a minimum of 15 to a maximum of 145.
Unfortunately, a statistical estimate of reliability within and between raters
was not provided. The potential advantages of this system include independent
accounting of specific scar types, thereby providing for separate atrophic and
hypertrophic subscores in addition to total scores. Potential shortcomings
include restriction to facial involvement, time intensivity and undetermined
clinical relevance of score ranges.
The Global Acne Scarring Classification is a four-category qualitative
system based on scar morphology and ease of masking by makeup or normal hair
patterns.
[23]
Severity levels progress from macular scarring (grade 1), mild atrophy or
hypertrophic scarring that may not be evident at 50 cm or greater and may be
adequately masked by makeup or hair patterns (grade 2), moderate atrophic or
hypertrophic scarring obvious at social distances and not easily masked (grade
3) and severe atrophic or hypertrophic scarring (grade 4). The extent of
involvement could also be indicated by the number of cosmetic units involved
with each severity grade of scarring. Finally, the authors present treatment
approaches relevant to the various severity grades. The strengths of this
system include simplicity, ease of application in practice and relevance to
patients and physicians with regard to corrective procedures. However, the use
of the term macular scarring in this grading system is confusing as is the
phrase 'oxymoronic'. Macules conventionally refer to flat areas of skin
distinguished by changes in skin color, while scars refer to thickening or
thinning of skin from prior disease or injury.
[24]
The use of the term 'postinflammatory macular dyspigmentation' may have been
more appropriate.
A quantitative global scarring grading system was also presented by the same
authors in which different types of scars were accorded increasing scores
(macular or mildly atrophic: 1 point; moderately atrophic: 2 points; punched
out or linear-troughed severe scars: 3 points; hyperplastic papular scars: 4
points).
[25]The
multiplication factor for these lesion types was based on the numerical range
whereby, for one to ten scars, the multiplier is 1; for 11-20 it is 2; and for
more than 20 it is 3. For hypertrophic/keloidal scars, scores are allocated
dependent on the size of these lesions, whereby an area of less than 5 cm
2
is 6 points, 5-120 cm
2 is 12 points and larger than 20 cm
2
is 18 points. The upper limit of this system has a score of 84. This system is
time-intensive and acknowledged by the authors to be cumbersome. While the
scoring scheme was shown to be reproducible between observers of 21 patient
photographs, a study of actual patients was not reported.
Psychosocial Impact
The onset of acne in adolescence coincides with developmental issues of body
image, socialization and sexual maturation. This temporal association may
partially explain the impact of acne on the psyche of the sufferer,
particularly on emotional health and self-perception. Furthermore, acne can
persist beyond teen years and lead to greater levels of psychosocial morbidity.
[26]
Acne patients have been found to have greater impairment in mental health
scores compared with patients with asthma, epilepsy, diabetes, back pain,
arthritis and coronary artery disease.
[27]
Acne has been associated with a variety of social and psychological
disturbances, such as embarrassment, anxiety, depression, suicidal ideation,
somatization and social inhibition.
[28-31]
In usual practice, the impact of acne on psychosocial factors and QoL has
largely been based on clinical impression rather than formal inquiry. However,
recent studies suggest that inferring the impact of acne from
physician-determined clinical measures of severity is inadequate and
inaccurate. The most severely affected acne patients differ from those who are
most severely impacted in QoL dimensions.
[26,32]
Although general health-status questionnaires were readily available and are
useful in comparing the impact of acne with other diseases, they have been
found to lack adequate sensitivity in detecting the psychosocial effects of
acne.
[33]
These shortcomings have led to the development of acne-specific psychometric
instruments with varying numbers of items (
Table 3 )
such as the Assessment of the Psychological and Social Effects of Acne (APSEA),
[34]
the Acne Disability Index (ADI),
[35]
the Cardiff Acne Disability Index (CADI),
[36]
the Acne Quality of Life Scale (AQOL),
[37]
the Acne Quality of Life (Acne-QoL)
[38-40]
and the abbreviated version of the latter, the Acne-Q4.
[41]
The APSEA was developed by selection of items from completion of five
different psychological and social disability questionnaires and the ADI.
[35]
Specific items demonstrating a significant difference in response between 200
acne patients and age- and sex-matched control patients without acne were
selected to establish the final questionnaire. In total, 15 items comprise the
APSEA, nine of which are scored on a linear visual analog scale from 0 to 10
and the remaining six scored by response selection with score allocation of 0,
3, 6 and 9. The maximum achievable score of 144 represents the greatest
disability. The test-retest correlation in 60 acne patients was significant at
0.99 (where 1.0 indicates perfect reliability). Although the mean completion
time was 2.16 min, the time required for score calculation was not provided.
Although none of the questions were specific for facial acne, the APSEA
correlated with facial acne grade but not total acne grade (which included
severity at the chest and back). A significant correlation was also noted
between APSEA score and acne duration, with females having persistent acne of
greater than 10 years showing higher disability levels compared with controls
and similarly affected males.
[34]
The ADI, a 48-item questionnaire completed with linear analog scales,
comprised eight domains: psychological, physical, recreation, employment,
self-awareness, social reaction, skin care and financial.
[35]
The questions were framed to the preceding 4 weeks and scoring was performed by
summation of item scores. Test-retest correlations were significant with a
reliability estimate of 0.96.
[33]
An abridged five-item version of this scale, entitled the CADI
[36]
was developed for routine clinical use. It also demonstrated high reliability
on test-retest, with an estimate of 0.98. The latter consisted of one question
each regarding psychological and social dimensions, interference with
activities, emotional state and overall severity of acne. Scoring was based on
responses and ranged from 0 to 3, with higher scores indicating greater
disability.
The AQOL was developed based on the need for an acne-specific QoL indicates
that was sensitive to changes in both acne severity and psychological morbidity
of acne.
[37]
Accordingly, this nine-item scale was derived from patient interviews,
literature review and factor analysis for correlation with indices of acne
severity and psychopathologic measures. Scoring was performed by summation of
responses based on a 0-3 scale for each item, with a maximum of 27. Higher
scores reflected greater morbidity. The test-retest reliability of this
instrument was significant at 0.99.
The Acne-QoL was developed specifically as an acne-specific psychometric
instrument for clinical trials in facial acne.
[38-40]
Comprised of 19 items within four domains (self-perception, role-emotional,
role-social and symptoms), each item is scored from 0 to 6 based on response
selections ranging from extreme (or extensive) to not at all (or none). Higher
scores reflect better health-related QoL. Developed by psychometric methodology
with extensive subject interviews, pilot testing and assessment of measurement
characteristics, this instrument has been demonstrated to be reliable, valid
and responsive. The reliability of this QoL within 1 week was significant at
0.84. However, the length of the 19-item Acne-QoL questionnaire and the
duration required for completion, approximately 5-7 min,
[38]
would likely preclude its use in routine clinical practice. Since many of the
items within the domains appeared redundant, an index of the parent instrument
was obtained by condensation to four items - one from each domain.
[41]
The items comprising the Acne-Q4 inquired about the following as a result of
facial acne: being dissatisfied with appearance, feeling upset, concern about
meeting new people and concern about scarring. The Acne-Q4 was shown to be
accurately reflective of the total score of the parent 19-item Acne-QoL, with a
correlation coefficient of 0.97. Thus, this abbreviated index may facilitate
the psychometric evaluation of acne patients in routine clinical practice by
its brevity.
Summary
The multiple scales available to evaluate clinical acne severity and scar
severity are an indicator of the inherent complexity of the undertaking. The
need for objectivity and precision may be best served by lesion counting, but
this method does not account for the totality of the presentation. Global
severity scales provide this perspective but may be more subjective and less
precise. However, greater reliability is observed when the assessments are
performed by the same rater. Patient-reported QoL measures provide a means of
obtaining objective, structured information from patients on the impact of acne
and provide the highest reliability estimates for all severity instruments. For
use in clinical practice, however, many of these QoL instruments are
impractical due to their length and associated completion time. Accordingly,
the use of validated indices or abbreviated versions of the parent instruments,
such as the Acne-Q4 and CADI, may be practical.
More than 15 years ago, an expert panel of the Consensus Conference on Acne
Classification recommended that grading of acne severity be based on lesional
type and extent, the presence of sinus tracts and ongoing scarring, adverse
psychosocial impact and recalcitrance to therapy.
[7]
Although a holistic scale combining all these elements is not currently
available, separate instruments are available for the measurement of these
individual elements. The combined information from these disparate but
inter-related elements of severity determination can inform caregivers by
providing a more complete perspective of the burden of acne on individual
patients.
Expert Commentary
Much of the recent literature in acne research is devoted to therapeutic
trials. However, methodological investigations into the accuracy and
reliability of clinical measures used in such trials are scarce. Proposals for
newer methods of acne-severity determination should be accompanied by
validation and reliability studies. Regulatory authorities have provided sound
guidance into appropriate measures of acne severity that are clinically
relevant and potentially universal in applicability. Combining the available
grading scales for severity of acne, acne scarring and QoL can provide a more
comprehensive representation of the burden of acne for the individual patient
and assist in guiding management.
Five-year View
While current guidance from regulatory authorities is helpful, their focus
is on the scientific basis of drug approval rather than individual patient
care. There is a need for the dermatological community to achieve consensus on
optimal measures of acne severity determination or, in their absence, to
support efforts in their development. Further validation studies of severity
scales are essential, as these are pivotal for decisions on treatment efficacy.
A greater focus on methodological underpinnings of research and drug trials,
particularly severity measures, will lead to the development of accurate,
reliable, relevant and universally applicable measures. A comprehensive
severity scale incorporating elements of acne activity, postacne scarring and
psychosocial impact would be of value to assist in holistic management. Ongoing
progress in imaging technology may enable further refinement in clinical
severity assessments.
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