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Original Article
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Sakchai Chaiyamahapurk, M.D., Ph.D.*, Prateep Warnnissorn, M.D., Ph.D.**
*Department of Community Medicine, **Department of Medicine, Faculty of Medicine, Naresuan University, Phitsanulok 65000, ailand.
Prevalence and Pattern of Diseases of The Skin and
Subcutaneous Tissue in A Primary Care Area in
Thailand
ABSTRACT
Objective: Information on the population-based prevalence study of skin diseases is still lacking. e study explores
the prevalence and pattern of diagnosed skin diseases of the population in a primary care area of a university
hospital in ailand.
Materials and Methods: Skin disease patients were identied using the International Statistical Classication of
Diseases and Related Health Problems 10
th
Revision codes (L00-L99). Retrospective data were obtained from the
hospital electronic medical record between 2015-2019. e number of clinic visits and the number of skin disease
diagnoses were counted. e ve-year period prevalence was calculated by dividing the number of cases by the
population in the primary care area.
Results: During the ve-year period, in a population of 29,969, we found 3,770 patients (12.6% of 29,969 population)
who made 7,433 outpatient visits with the diagnoses of skin diseases. Infections of the skin and subcutaneous tissues
were the most common (37.3%), followed by dermatitis (29.7%), urticaria and erythema (13.9%), other disorders
of the skin and subcutaneous tissue (8.6%), and papulosquamous disorders (1.7%). e ve-year period prevalence
of skin diseases per 100,000 persons was as following: cellulitis (2,296), urticaria (1,682), psoriasis (177), atopic
dermatitis (420), seborrheic dermatitis (227), alopecia areata (50), vitiligo (23), and pemphigus (10).
Conclusion: Infection and dermatitis were the two most common skin diseases in the primary care area population.
Atopic dermatitis, psoriasis, seborrheic dermatitis, and decubitus ulcer were less commonly found. Our prevalence
data should be the “at least” prevalence of skin diseases due to possible underreporting.
Keywords: Prevalence; skin disease; ailand (Siriraj Med J 2021; 73: 357-362)
Corresponding author: Sakchai Chaiyamahapurk
E-mail: sakchaich@nu.ac.th
Received 12 February 2021 Revised 18 March 2021 Accepted 19 March 2021
ORCID ID: http://orcid.org/0000-0001-5086-899X
http://dx.doi.org/10.33192/Smj.2021.47
INTRODUCTION
Skin diseases are one of the most common
presentations clinicians encountered in the daily practice.
ey are accounted for approximately 10.0% of a general
practitioner’s workload and 6.0% of outpatient referrals.
1
Skin conditions contributed 1.8% to the global burden of
disease measured in Disability-Adjusted Life Year from
306 diseases and injuries in 2013. Excluding mortality,
skin diseases were the fourth leading cause of disability
worldwide.
2
ere is still a lack of information on the population-
based prevalence study of skin diseases. Most studies on
the prevalence of skin disease report the percentage of
various skin diseases and use the medical record data
from mostly the tertiary care hospital which may not
reect the population they serve, therefore the prevalence
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358
of skin disease in the population could not be accurately
calculated.
ai national health insurance was overseen by
three dierent schemes: (i) the civil servants’ medical
benet scheme (ii) the social security scheme and (iii)
the universal coverage health scheme (72.0% of the
population).
3
Naresuan university hospital provided
health care for patients from all health scheme and also
had their primary care area covering ve subdistricts
surrounding the hospital. e population in these ve
subdistricts in year 2017 was 46,474. Among 46,474,
there were 29,969 who were registered under tax-funded
universal coverage health scheme. is study aimed to
explore the prevalence of skin disease in the population
of 29,969 in the primary care area of the hospital whom
were registered under the universal coverage health
scheme.
MATERIALS AND METHODS
We conducted a retrospective study using the hospital
electronic medical record database. All visits of skin
diseases diagnosed with the International Statistical
Classication of Diseases and Related Health Problems 10
th
Revision code for Diseases of the skin and subcutaneous
tissue (L00-L99) from January 2015 to December 2019
were collected. e given diagnosis, sex, age, date of
diagnosis, address, and health scheme were recorded
for each patient visit. At the date of the rst recorded
diagnosis, individuals were considered as prevalent
cases from that date onward. A patient who was seen
for the same diagnosis during the ve-year period was
counted as one case, regardless of the number of visits.
On the other hand, patients who received more than one
skin disease diagnosis were considered and counted as
separate cases for each of the diagnosis. e ve-year
period prevalence per 100,000 persons of various skin
diseases was calculated by dividing the accumulated
number of diagnosis cases from 2015 to 2019 with the
2017 year’s population (29,969 persons) which is in the
median of the ve years. Visits and cases of patients from
other health schemes were also analyzed and compared
with the universal coverage health scheme patients in
the primary care area. Statistical analysis was performed
using Stata, version 9.0 IC (Stata Corp LP, College Station,
TX, USA). is study was approved by the institutional
ethics review board with an IRB no. P3-007/2020.
RESULTS
During the ve-year period (2015-2019), out of
29,969 population living within the service areas and
registering with the universal coverage health scheme,
there were 3,770 cases and 7,433 visits with the diagnosis
of diseases of the skin and subcutaneous tissue (L00-L99).
e ve-year period prevalence of skin disease (L00-L99)
was 12,579 per 100,000 persons (3,770 x 100,000/29,969) or
12.6 percent for these population. Forty-six percent of the
patients were male. e mean, median, and interquartile
range of age were 33 years, 30 years, and 7-58 years,
respectively.
e frequency of skin disease diagnosis cases was
shown in Table 1. Infections of the skin and subcutaneous
tissues were the most common skin diseases (36.2%),
followed by dermatitis and eczema (31.3%), urticaria
and erythema (13.5%), other disorders of the skin
and subcutaneous tissue (8.6%), disorders of skin
appendages (8.3%) and papulosquamous disorders
(1.7%). Papulosquamous disorder patients and bullous
disorder patients had a high number of visits per case
with 6 visits per case and 9 visits per case, respectively.
A list of the prevalence of some selected skin
disorders is presented in Table 2. Dermatitis diagnosis
was the most common (19.6% of all skin diseases),
followed by cellulitis (18.2%) and urticaria (13.4%).
Alopecia areata, vitiligo, lupus erythematosus, lichen
planus, and pemphigus were more commonly seen in
female than male patients.
Fig 1 shows the distribution of age of patients with
various skin diseases. Fig 2 shows the seasonal variation
of skin disease with cellulitis becoming more common
during the rainy season.
e data of skin disease patients from other health
schemes who visited the hospital during the same period
was also analyzed. ere were 14,233 cases (28,977 visits)
which consist of dermatitis (35.8%), infections of the
skin and subcutaneous tissues (21.0%), urticaria and
erythema (16.2%), disorders of skin appendages (10.0%),
papulosquamous disorders (2.9%), bullous disorder
(0.7%), radiation-related disorder (0.7%), and other
disorder (12.6%).
DISCUSSION
In our study, the ve-year period prevalence of
diseases of the skin and subcutaneous tissue skin diseases
(ICD10 L00-L99) in the primary care area population
was 12,579 per 100,000 persons which translated into
approximately twelve percent of the population aected
by any skin diseases during the ve-year period. Infections
of the skin and subcutaneous tissues (36.2%), dermatitis
(31.3%), and urticaria (13.5%) were among the most
common skin diseases. A study from a hospital in Iran,
infections of the skin and subcutaneous tissues were
found to be the most common skin diseases (32.1%),
Chaiyamahapurk et al.
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TABLE 1. Frequency of diagnosed skin disease groups of population in the primary care area.
ICD-10 code ICD-10 description Visits % Cases % Prevalence*
L00-L08 Infections of the skin 2,382 32.4 1,366 36.2 4,560
L10-L14 Bullous disorder 89 1.2 10 0.3 30
L20-L30 Dermatitis 2,070 27.8 1,180 31.3 3,940
L40-L45 Papulosquamous 395 5.3 63 1.7 210
L50-L54 Urticaria and erythema 905 12.2 508 13.5 1,700
L55-L59 Radiation-related disorders 9 0.1 7 0.2 20
L60-L78 Disorders of skin appendages 543 7.3 312 8.3 1,040
L80-L99 Other disorders** 1,040 14.0 324 8.6 1,080
Total 7,433 3,770 12,579
*ve-year period prevalence per 100,000 persons calculated by (number of case / population of 29,969) x 100,000
**L80-L99 including such as vitiligo, seborrheic keratosis, lupus erythematosus, vasculitis, etc. ICD-10= International Statistical Classication
of Diseases and Related Health Problems 10th Revision
TABLE 2. Five-year period prevalence of selected skin diseases among universal coverage scheme population in the
primary care area.
ICD-10 Disease description Age Sex Cases Prevalence
code Mean % per 100,000
Median (IQR) male Number Percent* persons**
L30 Dermatitis 26, 13 (3-51) 44.5 738 19.6 2463
L03 Cellulitis 46, 53(25-65) 48.7 688 18.2 2296
L50 Urticaria 25, 18 {5-42) 42.4 504 13.4 1682
L23-L25 Contact dermatitis 30, 26 (7-49) 43.0 167 4.4 557
L20 Atopic dermatitis 17, 5 (0.6-25) 57.1 126 3.3 420
L40 Psoriasis 48, 52 (37-61) 49.1 53 1.4 177
L89 Decubitus ulcer 69, 73 (60-80) 38.9 49 1.3 164
L21-L22 Seborrheic dermatitis 20, 5 (0.2-38) 51.5 44 1.1 227
L63 Alopecia areata 29, 21 (15-47) 20.0 15 0.4 50
L80 Vitiligo 35, 18 (14-61) 28.6 7 0.2 23
L93 Lupus erythematosus 53, 55 {47-59) 33.3 6 0.2 20
L43 Lichen planus 61, 59 (56-65) 25.0 4 0.1 13
L10 Pemphigus 70, 66 (64-79) 0.0 3 0.1 10
*percent of all skin diseases (ICD-10 L00-L99) cases in primary care area ** ve-year period prevalence per 100,000 persons calculated by
(number of case/population of 29,969) x 100,000 IQR=interquartile range
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Fig 1. Age at the rst visit of skin disease
diagnosis (ICD-10 code) in ve-year
period sorted by the median of age.
L20=atopic dermatitis L30=unspecied
dermatitis L80=vitiligo L50=urticaria
L63=alopecia areata L40=psoriasis
L03=Cellulitis L93=lupus erythematosus
L43=lichen planus L10=pemphigus
Fig 2. Skin disease visits by the month
of the year
followed by dermatitis (24.5%), papulosquamous disorders
(3.8%), urticaria and erythema (2.8%).
4
A large hospital
network database study from Mexico, a study in a pediatric
dermatologic clinic in ailand, a study in ai elderly
patients showed infections as 32.1%, 21.9, and 21.9% of
all skin diseases, respectively.
5,6,7
e most common skin disease in a questionnaire
survey were warts (41.3%), followed by acne (19.2%)
and contact dermatitis (15.0%).
8
e global burden of
disease study showed 0.4% of burden for dermatitis
(atopic, contact, and seborrheic dermatitis), 0.3% for
acne vulgaris, 0.2% for psoriasis, 0.2% for urticaria, 0.1%
for pyoderma and cellulitis.
2
In our study, the proportion of patients with bullous
disorder and papulosquamous disorder in other health
schemes was higher than universal coverage scheme
in the primary care area, 2.9% versus 1.7 %, and 0.7%
versus 0.3%, respectively. A referral bias might explain
the dierence between two groups as patients with more
complex and serious diseases were more likely to require
a referral to our tertiary care hospitals.
Pemphigus, lichen planus, lupus erythematosus,
cellulitis, and psoriasis, tend to be the disease of adult
and elderly population as the median ages were above
40 years. Where as the median ages in patients with the
diagnosis of atopic dermatitis, unspecied dermatitis,
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vitiligo, urticaria, and alopecia areata were below 40
years. A study from the United States found that the
incidence rates of many skin diseases were aected by
age of the population.
9
In our study, dermatitis was the most common skin
problem; however, the terminology is oen nonspecic,
and may reect a variety of dermatitis conditions. e
prevalence of dermatitis is 2,463 per 100,000 persons.
A postal community survey from the United Kingdom
found dermatitis in 6,100 per 100,000 persons
10
, which is
higher than our study which used data from the electronic
medical record
e ve-year period prevalence of cellulitis was
2,296 per 100,000 persons. e number of cases were
higher during the rainy season, which could be related to
agricultural activities during the season. e incidence rate
of cellulitis in the US was 2,460 per 100, 000 person-years,
with a higher incidence among males and individuals
aged 45-64 years.
11
Urticaria prevalence in our study was 1,682 per 100,000
persons. In the studies from South Korea, and Taiwan, the
prevalence per 100,000 persons of chronic spontaneous
urticaria were 160-450, 690-790, respectively.
12,13
In our
study, atopic dermatitis prevalence of all age groups was
420 per 100,000 persons. e School survey study found
that the global prevalence per 100,000 persons of atopic
dermatitis in children aged 6-7 years was 7900.
14
e ve-year period prevalence per 100,000 persons
of psoriasis and seborrheic dermatitis was 177, and 227,
respectively. A community study in Turkey showed the
prevalence per 100,000 persons of psoriasis in people
older than 20 years of age was 1200, and the prevalence
of seborrheic dermatitis was 5,200.
15
In the estimation by
the Global Psoriasis Atlas website, psoriasis prevalence in
ailand was extrapolated at 0.3% (condence interval
0.06-1.65) or 300 per 100,000 persons.
16
Whereas seborrheic
dermatitis prevalence varies between 2.0% and 12.0%
throughout the world.
15
e ve-year period prevalence of alopecia areata
is 50 per 100,000 persons. e prevalence of alopecia
areata in South Korea was 155 per 100,000 persons.
17
e
ve-year period prevalence of vitiligo is 20 per 100,000
persons. Previous studies found that the prevalence of
vitiligo ranges from 60 to 2,280.
18
e ve-year period
prevalence of pemphigus is 10 per 100,000 persons. e
previous study found standardized point prevalence
pemphigus of 5.2 cases per 100,000 adults.
19
e prevalence of diseases depends on the study
design (hospital medical database analysis, cross-sectional
survey with medical exam, questionnaire survey), types of
measure (point, period, or lifetime prevalence), and case
denition (self-reported, physician’s, or dermatologist’s
diagnosis). We chose to report ve-year period prevalence
which allowed more time to detect more patients, so
more accurate data with chronic skin diseases but might
mix incident and prevalent case altogether.
e main limitation of our current study is by
using the data from the medical record instead of a
cross-sectional medical exam survey could lead to an
underestimation of the true prevalence. Most ve-year
prevalence of skin diseases in our study was still lower
than prevalence in other previous studies. e prevalence
in our study could be underreported from many reasons
such as patients with mild diseases might not have sought
clinical treatment, some might have tried over-the-counter
treatment from local pharmacies, or some may have
chosen to go to other health facilities. Our prevalence
data should be the “at least” prevalence of skin diseases.
e population included in this study was also relatively
small. Our studied population was the universal coverage
health scheme which tend to have lower socioeconomic
status and educational levels. Skin disease patients were
identied using ICD-10 code, L00-L99 (Diseases of the
skin, and subcutaneous tissue), which did not include
skin tumors, vascular disease such as a venous ulcer,
fungal, viral, and parasitic infection.
e strength of the study is the setting of denite
population in primary care area of a university tertiary
hospital, in which dermatology consultation was highly
accessible under the universal health coverage scheme.
CONCLUSION
In conclusion, during a ve-year period, 12.6 %
of the population in primary care was aected by skin
diseases. Among common skin diseases with a ve-year
period prevalence greater than 1.0% were dermatitis,
cellulitis, and urticaria. Atopic dermatitis, psoriasis,
seborrheic dermatitis, and decubitus ulcer were less
commonly found (prevalence less than 1.0% but more
than 0.1%). Vitiligo, alopecia areata, lupus erythematosus,
and pemphigus were the least common, less than 0.1%.
e nding would help to understand the burden of
skin disease for proper healthcare management, proper
medical training and disease prevention
Conict of interest: ere are no potential conicts of
interest to declare.
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