A major concern that has emerged from the coronavirus disease 2019 pandemic is patient avoidance of necessary medical care.1 Data regarding how in-person visits to medical facilities influence the risk of contracting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are limited. Obstetrical patients are a unique group who have required frequent in-person health care visits during the pandemic. The aim of this analysis was to examine whether the number of in-person health care visits was associated with the risk of SARS-CoV-2 infection.
Mass General Brigham institutional review board approval was obtained for this study and the need for informed consent waived. The study population included all patients delivering at 4 hospitals in the Boston, Massachusetts, area between April 19, 2020, and June 27, 2020, a period during which all obstetrical patients were tested for SARS-CoV-2 infection at the time of admission. All SARS-CoV-2 testing was performed on nasopharyngeal swabs using reverse transcriptase–polymerase chain reaction assays.
We performed a nested case-control study in which we used risk set sampling to match patients who tested positive for SARS-CoV-2 infection either during pregnancy or at the time of admission for labor and delivery with up to 5 control patients. The control matches were based on the gestational age of the cases and controls on the date the case tested positive for SARS-CoV-2 infection (±6 days), race/ethnicity (recorded in the patient’s medical record; Black vs Hispanic vs Asian or White), insurance type (Medicaid vs commercial), and SARS-CoV-2 infection rate in the patient’s zip code (divided in 20 groups by ventile).2
Based on electronic medical record data, we assessed the number of in-person visits for patients from March 10, 2020 (2 weeks prior to the closure of nonessential business in Massachusetts when community transmission was likely), to the date of the cases’ SARS-CoV-2 infection diagnosis. The association between the number of in-person visits and the odds of SARS-CoV-2 infection diagnosis was assessed using conditional logistic regression with adjustment for age, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), and essential worker occupation.3 We used multiple imputation to account for missing regression covariates (0.6% were missing BMI and 11.6% were missing essential worker occupation).
The odds ratios with corresponding standard errors were obtained from each of 10 imputed data sets and combined using the rules of Rubin4 to produce pooled estimates with 2-sided 95% CIs. We performed sensitivity analyses assessing the number of clinic visits after March 24, 2020 (the date of closure of nonessential businesses), excluding patients with a household member with known SARS-CoV-2 infection, patients testing positive for SARS-CoV-2 infection antenatally, and patients with incomplete covariate information. Precision around the measures of association is provided using 2-sided 95% CIs. Statistical analyses were performed using SAS software version 9.4 (SAS Institute Inc).
The study population included 2968 deliveries; 5 patients were not tested for SARS-CoV-2 infection and were excluded. There were 111 patients (3.7% [95% CI, 3.1%-4.5%]) who tested positive for SARS-CoV-2 infection. Of these 111 patients, 45 tested positive for SARS-CoV-2 infection antenatally and 66 tested positive at the time of admission for labor and delivery.
We excluded patients residing outside Massachusetts (2.2%) and those missing data required for matching (0.8%). We then matched 93 cases with 372 control observations. The mean number of in-person visits was 3.1 (SD, 2.2; range, 0-10) for cases and 3.3 (SD, 2.3; range, 0-16) for controls. For the association between the number of in-person health care visits and SARS-CoV-2 infection, the odds ratio was 0.93 (95% CI, 0.80-1.08) per additional visit. Sensitivity analyses yielded similar results (Table).
There was no meaningful association between the number of in-person health care visits and the rate of SARS-CoV-2 infection in this sample of obstetrical patients in the Boston area. Massachusetts had the third highest SARS-CoV-2 infection rate in the country during the spring 2020 surge, and the Boston area was particularly affected.
The findings from this obstetrical population who had frequent in-person visits to a health care setting and underwent universal testing for SARS-CoV-2 infection suggest in-person health care visits were not likely to be an important risk factor for infection and that necessary, in-person care can be safely performed. Limitations of this study include the restriction to obstetrical patients. Future studies are needed to determine whether these findings extend to other populations and health care settings.
Corresponding Author: Sharon C. Reale, MD, Brigham and Women’s Hospital, 75 Francis St, CWN L1, Boston, MA 02115 (screale@bwh.harvard.edu).
Accepted for Publication: July 28, 2020.
Published Online: August 14, 2020. doi:10.1001/jama.2020.15242
Author Contributions: Dr Reale and Ms Fields had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Reale, Lumbreras-Marquez, Huybrechts, Bateman.
Acquisition, analysis, or interpretation of data: Reale, Fields, Lumbreras-Marquez, King, Burns, Bateman.
Drafting of the manuscript: Reale, Bateman.
Critical revision of the manuscript for important intellectual content: Reale, Fields, Lumbreras-Marquez, King, Burns, Huybrechts, Bateman.
Statistical analysis: Reale, Fields, Burns, Huybrechts, Bateman.
Administrative, technical, or material support: Reale, Lumbreras-Marquez, Burns, Bateman.
Supervision: Reale, Bateman.
Conflict of Interest Disclosures: None reported.
Additional Contributions: We thank Julian Robinson, MD (Department of Obstetrics and Gynecology, Brigham and Women’s Hospital), and Ilona Goldfarb, MD (Department of Obstetrics and Gynecology, Massachusetts General Hospital), for comments on an earlier version of the manuscript. Neither of these individuals was compensated for their contributions.