DOI: 10.5061/dryad.xgxd254f9
title: Socioeconomic status affects the incidence of COVID-19 in Chilean multiple sclerosis patients

description: Objective: To investigate the frequency of coronavirus disease
 (COVID-19) in patients with multiple sclerosis (pwMSs) living in a high
 socioeconomic vulnerability area in Chile. Methods: In this
 prospective cohort study, we compared the frequency of COVID-19 in 52
 Chilean pwMSs on disease-modifying treatments (DMTs), living in urban
 municipalities with low-income/high-poverty levels, with that previously
 reported in pwMSs living in municipalities with high-income/low-poverty
 rates in Santiago, Chile. Demographic and clinical features of the pwMSs
 were obtained from their last consultation between March 3, 2020, and
 August 29, 2020. Results: In the low-income pwMSs, the mean
 patient age was 34 years, 69% were women, mean disease duration was 3
 years, and mean Expanded Disability Status Scale score was 1.6. Of these,
 61.5% pwMSs (32/52) underwent quarantine during the study period. COVID-19
 diagnosis was confirmed by reverse transcriptase polymerase chain reaction
 in five patients (10%): two were on glatiramer acetate, one was on
 fingolimod, and two were on alemtuzumab. All pwMSs with COVID-19 recovered
 fully. The previously reported frequency of confirmed COVID-19 in
 middle‒upper income pwMSs living in Santiago was 1%. The frequency of
 COVID-19 among pwMSs in the low- and middle‒high income inhabitants of
 Santiago differed significantly (z = -4.3235, p &lt; 0.00001;
 one-tailed Fisher exact test, p &lt; 0.01). Conclusion: The
 frequency of COVID-19 in the low-income/high-poverty cohort in Santiago,
 Chile, was markedly high. Accordingly, high socioeconomic vulnerability
 should be considered as an important risk factor for COVID-19 in pwMSs.
description: This was a prospective cohort study that included 52 adults with
 MS defined according to the revised McDonald criteria. These pwMSs were
 followed-up at the University of Chile Hospital and San Juan de Dios
 Hospital, Santiago, Chile. Inclusion criteria were age 18 years or older,
 a minimum of 5 months of follow-up per patient during the COVID-19
 pandemic, with an entry assessment in March (since March 3rd, 2020) and at
 least a second assessment at month 5 (until August 29th, 2020). Direct
 interviews between the patients and the treating neurologists were part of
 the inclusion criteria. These interviews were conducted during the
 hospital appointments, hospitalization for DMT infusions or COVID-19
 treatments, or over the telephone. Online questionnaires were not used.
 Patients with clinically isolated syndrome were excluded. This study was
 part of routine clinical practice, and therefore, the treating
 neurologists were free to make any therapeutic change. Because of the
 observational nature of the study, no further inclusion criteria were
 defined. We note that these two hospitals provide medical assistance to
 patients living in municipalities with higher poverty rates than the
 average in Santiago of Chile, both in terms of income and of
 multidimensional poverty. Multidimensional poverty is defined as a
 composite index consisting of scores assessed in four dimensions:
 Education, Health, Work and Social Security, and Housing. It is an
 official supplementary measure for the income-based national poverty index
 in Chile. We further assessed the association of MS
 with COVID-19 by comparing a matched sample with our original cohort. To
 achieve this, we contacted our original participants, re-interviewed them
 in order to obtain new information, and then found a person similar in
 terms of sex and age living in the same neighborhood. The process of
 contacting the matching cases was carried out directly by the research
 team, and the non-MS participants were interviewed via phone. This
 complementary survey strictly referred to the study period (March 3, 2020
 to August 29, 2020). We obtained a matched sample of 52 pairs of
 participants, each pair sharing the same sex and age group and living in
 the same neighborhood. The average estimated distance between the
 households of the pwMSs and their controls was 106 meters (SD: 103.9). We
 used the body mass index (BMI) to define overweight (BMI 25–29.9) and
 obesity (BMI &gt;30). Physical activity was described as sedentary
 behavior, light intensity physical activity, and moderate physical
 activity.16,17 We used a direct self-report measure of income based on the
 National Socioeconomic Characterization Survey. We included the number of
 residents, bedrooms, and bathrooms in the households of both PwMSs and
 their matched controls. All patients were surveyed by
 questionnaire on demographic and clinical features, on whether they had
 followed the World Health Organization’s guidelines on preventive measures
 for reducing COVID-19 transmission, including social distancing and
 frequent hand-washing with soap and water or alcohol-based hand sanitizer.
 According to the ISN guidelines, the participants were also asked whether
 they followed governmental guidelines on facemasks and quarantine.
 Additional questions centered on whether they had been in contact with a
 person with SARS-CoV-2 infection or had experienced COVID-19-related
 symptoms. Cases with suggestive symptoms were assessed by SARS-CoV-2
 polymerase chain reaction (PCR) testing on a nasopharyngeal swab. Absolute
 lymphocyte counts (ALC) obtained during the COVID-19 pandemic were
 reported for patients with natalizumab, ocrelizumab, and alemtuzumab.
 Lymphopenia was defined as grade 1: ALC 800‒999/ul; grade 2: ALC
 500–799/μl; grade 3: ALC 200‒499/μl and grade 4: ALC &lt;
 200/μl. Statistical analysis
 Analyses of the clinical data and clinical-imaging correlations
 were performed using the Statistical Package for Social Sciences (IBM
 Corp., Armonk, NY, USA, version 22). The results are presented as the mean
 ± standard deviation (SD).  In all cases, a two-sided p value of
 &lt;0.05 was considered significant. Monthly income, BMI, and measures
 related to household members were compared using a two-tailed
 t-test.  Fisher´s exact test was used to compare proportions between pwMSs
 and their neighbors. We compared differences in the proportion of pwMSs
 with COVID-19 in this cohort with that in other cohorts in Chile recently
 reported in the literature. Study 1 was based on an online sample drafted
 from pwMSs at a single, private MS-treatment center and residing in more
 socioeconomically advantaged areas in Santiago, Chile, and reported a
 frequency of COVID-19 among pwMSs of 1.1%.19 Another national multicentric
 investigation, involving 327 pwMSs (79%) with private medical insurance
 and 77 pwMSs (19%) with public medical insurance, by the same team as
 Study 1, reported a frequency of COVID-19 among pwMS of 3.5%, based on
 online surveys.20 Study 1 and Study 2 started at the beginning of the
 pandemic in Chile, but they closed earlier that ours (Study 1 closed in
 May 7th and Study 2 in June 22sd).  To assess if the differences in
 COVID-19 proportions between this study and previous ones were
 significant, we performed both a z-test and Fisher’s exact test for two
 reasons. 1) The z-test is a proportions test used to determine whether two
 population proportions are different when the variances are known and the
 sample size is large; in this case, because of the total sample size, we
 used it to identify initial differences. 2) Fisher's exact test is a
 chi-square-based test, which, because of its exact calculation, is
 appropriate for small sample sizes; we used Fisher’s exact as a way to
 confirm the initial differences found by z-tests.