Abstract
Objectives: To estimate the rate of scabies diagnostic recurrence and identify factors associated with the high likelihood of frequent scabies recurrences among adults in Saudi Arabia.
Methods: This multi-center retrospective study was conducted in adult patients who were diagnosed with one or multiple recurrent infestations of scabies between January 2016 and September 2018 at the Ministry of National Guard-Health Affairs hospitals and clinics, Saudi Arabia. The number of scabies recurrences during the study period was recorded and modeled using a Poisson model.
Results: A total of 468 adult patients (39.8±17.8, range: 14.2-105.7 years) were included in the study, resulting in 645 scabies diagnoses in which 302 (46.8%) were recurrences. The multivariate Poisson model revealed that male gender (adjusted rate ratios [aRR]: 1.465; 95%CI: 1.064 - 2.017; p=0.019), first tertile (January to April) (aRR: 3.021; 95%CI: 1.484 - 6.149; p=0.002), and high humidity (aRR: 1.066; 95%CI: 1.002 - 1.133; p=0.043) had a higher likelihood of frequent scabies recurrences.
Conclusion: The rate of scabies recurrence among adult patients in Saudi Arabia was high, and is comparable with previous report in Japan. The study suggests that male gender, first tertile, and high humidity were independently associated with the high rate of scabies recurrences among adults. An interventional program to lower the rate of scabies recurrences and prevent outbreak should be undertaken.
Worldwide, it has been estimated that 300 million cases of scabies occur annually.1 Scabies can be transmitted by direct contact with the person’s skin, or indirectly by sharing clothes, towels, bedding, and others objects used by an infected person.2 Scabies can affect families, and particularly those living in poor conditions and with limited access to healthcare.3 Scabies can occur in any geographical location; however, the highest global rates of scabies (71.4%) were reported in tropical regions with humid climates.3,4 Pruritus is the most frequently diagnosed skin condition of scabies, which can progress to become bacterial infections and potentially can become a life-threatening condition.5 Reports on indicators and prevalence of scabies in Saudi Arabia have been limited to closed communities, such as observed cases among workers residing in crowded neighborhoods;6 however, at the start of the year 2018, there were outbreaks of this highly contagious disease in the Western region of the Kingdom, and additional outbreaks have been reported in other regions. It is unclear whether these outbreaks were imported from the Western region. Despite the continuous sporadic reports about new cases, which are generated by the Ministry of Health for different regions in Saudi Arabia, there is no official documentation of the epidemiological aspects and main determinants of scabies infestation. In addition to the lack of reports on the number and distribution of the cases of scabies, the reasons for the recurrent infestations after an initial infestation are poorly understood. Studies have reported high recurrence rate of scabies7,8 and its most likely to happen in hospitalized patients with no significant correlation evident in community-acquired cases. This study aimed to estimate the rate of scabies diagnostic recurrences and identify factors associated with the high likelihood of frequent scabies recurrences in patients who were diagnosed with one or multiple recurrent scabies outbreaks between January 2016 and September 2018 at the Ministry of National Guard-Health Affairs (MNGHA) hospitals and clinics, Saudi Arabia.
Methods
A multi-center retrospective study was conducted on patients who were diagnosed with one or multiple scabies recurrences between January 2016 and September 2018 at the MNGHA hospitals and clinics, Saudi Arabia (Western, Central, and other regions). The study included patients from major MNGHA hospitals and clinics such as King Abdulaziz Medical City, Riyadh; King Abdulaziz Medical City, Jeddah; Imam Abdulrahman Bin Faisal Hospital, Dammam; King Abdulaziz Hospital, Al Ahsa; and, Prince Mohammad bin Abdulaziz Hospital, Madinah. The study obtained approval (# RC18/220/R) from the Ethics Committee at MNGHA. The patients’ consent to review their medical records and publish research findings was not required by the Ethics Committee. Data were reported from 24 MNGHA hospitals and clinics across Saudi Arabia. The database group at King Abdullah International Medical Research Centers (KAIMRC) identified patients who were diagnosed with scabies during the period of the study, as these patients were evaluated and managed at the MNGHA hospitals and clinics across Saudi Arabia.
In 2015, the MNGHA implemented a new electronic health information system, called BestCare9,10 and data for this study were extracted from the BestCare system. This unified database allows integration of all MNGHA hospitals and clinics across Saudi Arabia. All diagnoses and medication histories are stored in chronological order. The data included gender, age, region where a case was diagnosed, and tertiles of the year: first (January to April), second (May to August), and third (September to December). Data on climate factors (based on Google reports) were gathered by calculating the monthly average of ultraviolet index, temperature (°C), rainfall (mm), humidity (%), cloud (%), and winds (kmph). We retrieved data on the clinics where patient received scabies diagnoses: emergency room and satellite clinic.
The diagnosis was based on clinical signs with the presence of the following: “scabies burrows,” “typical lesions affecting male genitalia,” or “typical lesions in a typical distribution and 2 history features,”11 and physicians often considered microscopy to confirm some cases. The study included all patients 14 years of age or older who were treated from one or multiple recurrences of scabies. We excluded patients who had follow-up treatment for scabies. More description of the methods can be found in our previous report on children.12
We defined the study outcome to be the number of scabies recurrences after an initial diagnosis during the study period. The number of scabies recurrences was found to be clustered (from 0 to 7), where “0” indicates a single diagnosis or no recurrence, and 1 to 7 indicate the number of recurrences. A total of 468 adult patients were included in the study, resulting in 645 scabies diagnoses during the study period.
Statistical analyses
Data analysis was performed by the Statistical Package for Social Sciences, version 20.0 (IBM Corp, Armonk, NY, USA). A descriptive of the sample is presented in Table 1. The study outcome was treated as discrete counts, which is the number of scabies recurrences, and was analyzed by Poisson model. We compared the goodness-of-fit of negative binomial and Poisson models using deviance values. We assessed bivariate unadjusted and multivariate adjusted rate ratios (RR and aRR) of scabies recurrences and a 95% confidence interval (CI), which were calculated and presented in Table 2. A 2-tailed p value of <0.05 was regarded as a significant association with a greater frequency of scabies recurrences.
Patient's characteristics and monthly climate data (N=468).
Predictors of high rate of scabies recurrence.
Results
A total of 468 adult patients were included in the study, resulting in 645 scabies diagnoses in which 302 (46.8%) were recurrences with a CI between 42.9% and 50.8%. Figure 1 shows frequency of scabies recurrences. The sample of 468 adult patients comprised 57.7% males, and 61.1% were diagnosed in the Western region of Saudi Arabia. The mean age was 39.8 years (±SD 17.8) with an age range between 14.2 and 105.7 years. More descriptive of the sample can be found in Table 1.
Frequency of recurrence of scabies.
The bivariate Poisson models (Table 2) identified male gender (RR: 1.505; 95% CI: 1.099-2.059; p=0.011), and high humidity (RR: 1.020; 95% CI: 1.002-1.037; p=0.028) to be significantly associated with a greater rate of scabies recurrences. Low ultraviolet (RR: 0.889; 95% CI: 0.812-0.974; p=0.011) and low temperature (RR: 0.977; 95% CI: 0.959-0.997; p=0.021) were associated with a lower rate of scabies recurrences.
The multivariate Poisson model (Table 2) revealed that male gender (aRR: 1.465; 95% CI: 1.064-2.017; p=0.019) had a higher rate of scabies recurrences. The first tertile (January to April) had a higher rate of scabies recurrences (aRR: 3.021; 95% CI: 1.484-6.149; p=0.002) as compared to the third tertile (September to December). There was an increased rate of scabies recurrence as humidity increases (aRR: 1.066; 95% CI: 1.002-1.133; p=0.043).
Goodness of fit shows that the Poisson model is a suitable approach for this data when compared to the negative binomial regression model: (deviance value: 1.069 versus 0.761).
Discussion
This is a retrospective study of the largest cohort of patients with scabies reported in Saudi Arabia. Over the past few years, a number of ineptly documented scabies outbreaks have occurred in Saudi Arabia, with greater effect in a school setting and crowded residential area,6 and which is probably attributed to the cluster infections,11 Causes of scabies outbreaks remain unclear in Saudi Arabia.12
No data exists on scabies recurrence in Saudi Arabia or the Gulf region and it has not been widely reported worldwide. The rate of scabies recurrence was 46.8% which is high in our population, consistent with previous report in Japan 44.3%8 (Chi-squared=0.930, p=0.335). These high recurrence rates may require routine patient therapy compliance and close monitoring, which can be effective in reducing the burden of scabies. A large prospective study is needed to assess whether scabies recurrence is the result of certain treatments. We observed a significantly higher scabies recurrence rate in the first tertile (January to April) as compared to the third tertile (September to December). In March and April 2018, several outbreaks of scabies occurred involving multiple schools and crowded residential areas. Scabies recurrence may be attributed to the effect of climate factors. The study has showed that as relative humidity has increased by 1%, the rate of scabies recurrence tends to increase by 6.6%. This is similar to a nationwide study in Taiwan where the incidence was positively correlated with relative humidity.13 We observed a higher rate of scabies recurrence in male gender, inconsistent with report from Japan where gender was insignificantly associated with scabies recurrence.8 This conflicting finding could be due to the variation in study populations as patients in our sample were younger (mean of 39.8 years) than the study in Japan (mean of 82.5 year).
This study used a multi-center to address the recurrence rate of scabies and its factors among adult patients in Saudi Arabia. Given the rarity of the topicin Saudi population, this report in adult patients highlights the fact that scabies recurrence exists and is frequently common, thus, intervention is needed to prevent reinfestation.12
Study limitations
There are several limitations to the study. The study used retrospective design to evaluate associations rather than causations, thus interpretation must be drawn carefully. The study design also resulted in a lack of available data on clinical signs, proscribed treatment, and comorbidities. The study population is restricted to scabies diagnoses made in MNGHA hospitals and clinics.
In conclusion, the rate of scabies recurrence among adult patients in Saudi Arabia was high, and is comparable with previous report in Japan. The study suggests that male gender, first tertile, and high humidity were independently associated with the high rate of scabies recurrences among adults. An interventional program to lower the rate of scabies recurrences and prevent outbreak should be undertaken.
Footnotes
Disclosure. Authors have no conflict of interests, and the work was not supported or funded by any drug company.
- Received August 8, 2019.
- Accepted November 24, 2019.
- Copyright: © Saudi Medical Journal
This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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