A Systematic Review of Epidemiologic Studies on Scabies in the Philippines

Abstract

Background and objective: Scabies is the second most common cause of disability due to skin disease in the Philippines. However, there were no cited studies in Global Burden of Disease 2019 and the disability-adjusted life years (DALY) computations were most likely based on statistical modelling. The Philippine Department of Health has embarked on a program to estimate the disease burden of priority diseases in the country, which include scabies. The last nationwide prevalence survey was 23 years ago. This systematic review aimed to estimate the prevalence or incidence of scabies in the Philippines.

Methods: We searched PubMed, Scopus, Herdin, and Philippine Health Research Registry (search date October 2022) for studies on prevalence/incidence (including systematic reviews, cross-sectional studies, cohort studies, case series, registry or census studies) of patients diagnosed with scabies in the Philippines. We excluded narrative reviews, commentaries, and conference proceedings or abstracts. Two reviewers independently screened titles and abstracts, assessed full text reports for eligibility, appraised the quality of included studies, and collected data using a pretested data extraction form. We did not pool studies due to clinical heterogeneity but plotted the individual studies in a forest plot with prevalence estimates and confidence intervals. We reported the median and interquartile range for entire group or relevant subgroups (age, setting) of studies. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the certainty of evidence.

Results: We included nine studies (N=79,065). Most were clinic-based prevalence studies, retrospective chart reviews, conducted in dermatology outpatient clinics, Metro Manila area, and on pediatric populations. Prevalence of scabies was moderate (i.e., between 2 and 10%), ranging from 2.75% (national prevalence survey) to 6.8% (community-based review), to high (> 10%) among pediatric patients in clinic-based retrospective chart reviews (29 to 36%) and institution-based surveys (39.0% to 45%), and a tertiary government university training hospital dermatology clinic (22.9%). The most affected age group was from 0 to 14 y/o, while males tended to have a higher prevalence than females. The cooler month of January had higher prevalence than the hotter month of June in one study.

Conclusion: Scabies is common in the Philippines, especially among children and elderly in institutional settings, and during the month of January. There is a need to do a national prevalence survey to identify high-risk areas and to monitor the prevalence of scabies, especially in crowded settings and vulnerable populations. This information can be used for estimating the burden of disease for scabies and guide appropriate health resource allocation.

Keywords: Philippines; epidemiology; incidence; prevalence; scabies; surveillance.

Figure 1

PRISMA flow diagram.

Figure 2

Forest plot for prevalence of scabies cases, subgroup by setting.

Figure 3

Forest plot of prevalence, subgroup by age group.

Figure 4

Forest plot of prevalence, subgroup by sex.