- This large, population-based U.S. study compared 2,701 patients with rheumatic and musculoskeletal diseases who were diagnosed with COVID-19 between January 20 and April 19, 2020, with the same number diagnosed April 20 to July 19, 2020
- The two cohorts were matched on demographics, comorbidities, specific diagnoses, creatinine, body mass index, glucocorticoid use, use of oral disease-modifying antirheumatic drugs, biological DMARD use and previous hospitalizations
- The risks of all prespecified 30-day outcomes were substantially lower for the late cohort than the early cohort
- Still, even in the late cohort, 32% of patients were hospitalized, 14% developed acute kidney injury, 8% were admitted to the ICU, 4% were mechanically ventilated and 4.5% died
- Furthermore, 11% of patients in the late cohort met a composite outcome of ICU admission, mechanical ventilation or death
Studies conducted early in the COVID-19 pandemic showed mixed results on whether patients with rheumatic and musculoskeletal diseases have more severe outcomes than the general population. It is not clear how recent improvements in COVID-19 care have affected the risks for these patients.
Researchers at Massachusetts General Hospital compared patients with rheumatic and musculoskeletal diseases who developed COVID-19 in the first 90 days of the pandemic or the subsequent 90 days. In The Lancet Rheumatology, April Jorge, MD, rheumatologist, Kristin M. D'Silva, MD, fellow, and Hyon Choi, MD, program director of the Clinical Epidemiology Program and clinical rheumatologist in the Division of Rheumatology, Allergy and Immunology (RAI), report that the risks of death and other severe outcomes have improved but are still substantial.
The researchers used U.S. data from TriNetX, a research network that provides real-time updates of electronic health record data on 51 million patients in 36 health care organizations. They identified 2,811 patients with rheumatic and musculoskeletal diseases who were diagnosed with COVID-19 in the early cohort (January 20 to April 19, 2020) and 5,729 in the late cohort (April 20 to July 19, 2020).
The team matched patients 1:1 according to demographics, comorbidities, rheumatic and musculoskeletal disease diagnoses, creatinine, body mass index, glucocorticoid use, use of oral disease-modifying antirheumatic drugs, biological DMARD use and previous hospitalizations, using an exposure score method analogous to propensity score matching.
After matching, there were 2,701 patients in each cohort. Prespecified outcomes were assessed between the date of COVID-19 diagnosis and 30 days later.
- Risk of hospitalization: 45% in the early cohort vs. 32% in the later cohort (RR, 0.71)
- Acute kidney injury: 21% vs. 14% (RR, 0.66)
- Acute renal failure requiring initiation of renal replacement therapy: 1.2% vs. 0.6% (RR, 0.53)
- ICU admission: 14% vs. 8% (RR, 0.56)
- Mechanical ventilation: 9% vs. 4% (RR, 0.39)
- Death: 9% vs. 4.5% (RR, 0.48)
- Composite of ICU admission, mechanical ventilation or death: 22% vs. 11% (RR, 0.51)
The research team then exposure-matched the subgroup of patients with rheumatic and musculoskeletal diseases who were hospitalized within seven days of COVID-19 diagnosis. For the 1,089 patients in each cohort:
- Risk of acute kidney injury: No significant difference between the early and late cohorts
- Acute renal failure: No significant difference
- Composite outcome: 41% vs. 31% (RR, 0.74)
Interpreting the Findings
Improvement in COVID-19 outcomes over time in patients with rheumatic and musculoskeletal diseases could be due to improvements in therapies and supportive care, as well as higher testing capacity allowing detection of milder COVID-19 cases. In the hospitalized subgroup analysis, the two cohorts had more similar illness severity and the differences between them were attenuated. This supports the proposition that the improvements in the primary analysis are at least partly attributable to temporal changes in illness severity at the time of COVID-19 diagnosis.
Still, the death rate in the late cohort was 4.5%, similar to estimates for the general U.S. population as of August 2020. COVID-19 continues to be a potentially severe disease, and major improvements in prevention and treatment are still urgently needed.
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