Evolving Phenotypes of non-hospitalized Patients that Indicate Long Covid

Estiri, H.; Strasser, Z.; Brat, G.; Semenov, Y.; Patel, C.; Murphy, S.

Many of the symptoms characterized as the post-acute sequelae of SARS-CoV-2 infection (PASC) could have multiple causes or similarly seen in non-COVID patients. Accurate identification of phenotypes will be important to guide future research and the healthcare system to focus its efforts and resources on adequately controlled age- and gender-specific sequelae of COVID-19 infection. In this retrospective electronic health records (EHR) cohort study, we applied a computational framework for knowledge discovery from clinical data, MLHO, to identify phenotypes that positively associate with a past positive PCR test for COVID-19. We evaluated the post-test phenotypes in two temporal windows at 3-6 and 6-9 months after the test and by age and gender. We utilized longitudinal diagnosis records stored in EHRs from Mass General Brigham (MGB) 57 thousand patients who tested positive or negative for COVID-19 and were not hospitalized. Statistical analyses were performed on data from March 2020 to March 2021. PCR test results and subsequent diagnosis records that were recorded for the first time two months or later after the PCR test. We identified 28 phenotypes among different age/gender cohorts or time windows that positively associated with past SARS-CoV-2 infection. All identified phenotypes were newly recorded in patients' medical records two months or longer after a COVID-19 PCR test in non-hospitalized patients regardless of the test result. Among these phenotypes, a new diagnosis record for anosmia and dysgeusia (OR 2.17, 95% CI [1.42 - 3.25]), alopecia (OR 3.54, 95% CI [2.92 - 4.3]), chest pain (OR 1.35, 95% CI [1.16 - 1.56]), or chronic fatigue syndrome (OR 1.81-2.28, 95% CI [1.38 - 3.68]) are the most significant indicators of a past COVID-19 infection, especially among women younger than 65. Among men, edema (OR 1.83, 95% CI [1.23 - 2.66]) and disease of the nail (OR 3.54, 95% CI [1.63 - 7.29]) in patients 65 and older or proteinuria (OR 2.66, 95% CI [1.61 - 4.34]) in patients under 65 are associated with a positive COVID-19 PCR test in the past few months. Our approach avoids a flood of false positive discoveries while offering a more probabilistic flexible criterion than the standard linear phenome-wide association study (PheWAS). These findings suggest that some of the previously identified post sequelae of COVID-19 may not be accurate and that most of the PASC are observed in patients under 65 years of age.