Prevalence and descriptive epidemiology of atopic dermatitis and its impact on quality of life in Singapore

Dear Editor, Atopic dermatitis (AD) is a common, chronic, pruritic skin condition that is known to have a negative impact on patients’ quality of life (QoL).1,2 Due to its increasing prevalence, AD can impose a substantial economic burden on a country's healthcare system.3 A study in 2002 found a prevalence of 20·8% of AD in Singaporean schoolchildren aged 7–12 years.4 However, more recent studies in other developed countries have shown a higher prevalence of AD.5,6,7 The aim of our study was to determine the prevalence and descriptive epidemiology of AD, other forms of eczema (asteatotic, seborrhoeic, discoid and stasis) and related conditions (ichthyosis vulgaris, keratosis pilaris, pityriasis alba) in Singaporean adults and children, and to investigate the impact of these conditions on QoL. We performed a community‐based, cross‐sectional survey of Singaporeans and permanent residents between the ages of 1 and 80 years. Volunteers were recruited from 20 randomly selected housing blocks across Singapore and were assessed in their homes by 30 trained medical students. The U.K. Working Party Diagnostic Criteria for Atopic Dermatitis were employed to determine a diagnosis of AD. The European Quality of Life Five Dimensions (EQ‐5D), Dermatology Life Quality Index (DLQI) and Children's DLQI were used to assess the impact on QoL. A physical examination was offered to all participants and the Investigator's Global Assessment score was used to determine the severity of AD. The study was designed and carried out in accordance with the ethical principles set forth in the Declaration of Helsinki. The research plan was reviewed and approved by a research ethics committee convened by the Saw Swee Hock School of Public Health, National University of Singapore. Informed consent was obtained from all individuals, or their parents or legal guardians if they were < 21 years of age. No identifying information of the study participants was collected at any point in time. Of 2023 households approached, 845 (41·8%) responded. Of these, 794 were eligible and 546 (68·8%) consented to participate in this study. There were a total of 1110 eligible volunteers who completed the questionnaire, and 681 individuals agreed to be physically examined. These 681 individuals formed our study sample. There were 379 (55·7%) female and 302 (44·3%) male respondents. There were 531 (78·0%) Chinese, 63 (9·3%) Malay, 70 (10·3%) Indian and 17 (2·5%) from other races, reflecting the overall racial distribution of Singapore. Volunteers aged ≤ 18 years (children) made up 20·7% of our cohort, while 79·3% were aged > 18 years (adults). The overall prevalence of AD was 13·1% (89 of 681), with a higher prevalence in children (20·6%) than in adults (11·1%). In total, 57% of the cases had onset of AD before 20 years of age. The most common sites of involvement were the cubital fossae (52%), popliteal fossae (42%) and neck (34%). The most common aggravating factors reported were hot weather (67%), exposure to dusty environments (48%) and physical exercise (30%). A personal history of allergic rhinitis and asthma was reported by 56% of the cases. A family history of atopy was reported by 46%. The two most common treatments were topical corticosteroids (56%) and moisturizers (48%). Overall, 15% of the cases were not on any form of treatment. The severity of AD at the time of examination was clear in 45%, almost clear in 33%, mild in 13% and moderate in 9%. The prevalences of other skin conditions evaluated in our study were low, and included discoid eczema (1·0%), seborrhoeic dermatitis (0·9%), asteatotic eczema (0·3%), stasis eczema (1·9%), keratosis pilaris (1·0%), pityriasis alba (1·3%) and ichthyosis vulgaris (1·8%). With regard to the impact of AD on QoL, 29% of participants with AD reported one or more problems on the EQ‐5D health descriptive system, compared with 22·6% without AD (P = 0·17), while 89% of participants with AD and 77·4% of participants without AD reported suboptimal global health using the EQ‐5D visual analogue scale (P = 0·016) (Table 1). We observed that 68% of participants with ‘clear’ skin at examination, 56% of participants with ‘almost clear’ skin, 78% of participants with ‘mild AD’ and 100% of participants with ‘moderate AD’ reported suboptimal DLQI scores. The association between skin conditions and quality of life CI, confidence interval. EQ‐5D, European Quality of Life Five Dimensions. The association between skin conditions and quality of life CI, confidence interval. EQ‐5D, European Quality of Life Five Dimensions. This study confirmed the high prevalence of AD in the Singapore population, with a higher prevalence in children than in adults. Similar to other studies,4 we found that dust and heat were reported as common aggravators for AD. These findings suggest that policy measures to improve ventilation facilities in schools or workplaces may help reduce AD flares in our hot tropical climate. We found a relatively high number of participants with AD who were not on treatment. Proper education on regular treatments in AD should be instituted, in addition to finding better moisturizers to suit Singapore's hot and humid environment. In conclusion, our community‐based study has shown a high prevalence of AD in Singapore, especially among children. The prevalence of other associated skin conditions such as stasis eczema or discoid eczema is low. Individuals with AD experience a lower QoL than those without AD. Future studies to establish the long‐term health and economic burden of AD and its associated conditions would be of value. Funding sources: none. Conflicts of interest: none declared.