Summary box
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A subsection of the population infected with SARS-CoV-2 go on to experience post-COVID-19 condition or long COVID.
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Preliminary findings, such as case reports of post-COVID-19 immune-mediated inflammatory diseases, increased autoantibodies in COVID-19 patients, and molecular mimicry of the SARS-CoV-2 virus have given rise to the theory that long COVID may be due in part to a deranged immune response.
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SARS-CoV-2 infection was associated with a 22% relative increase in the risk of developing certain immune-mediated inflammatory diseases, including type 1 diabetes mellitus, inflammatory bowel disease, and psoriasis.
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These findings support the hypothesis that a subgroup of long COVID may be caused by immune-mediated inflammatory mechanisms.
Background
Methods
Study design and data source
Study population
Exposure
Outcomes
Follow-up period
Covariates
Statistical analysis
Results
Study population
Characteristics | Exposed cohort (n = 458,147) | Unexposed cohort (n = 1,818,929) |
---|---|---|
Sex, n (%) | ||
Male | 207,514 (45.3) | 823,988 (45.3) |
Female | 250,633 (54.7) | 994,941 (54.7) |
Age (years) | ||
Mean (SD) | 43.6 (17.1) | 42.8 (18.0) |
Age categories, n (%) | ||
18–29 | 113,618 (24.8) | 478,811 (26.3) |
30–39 | 94,499 (20.6) | 377,117 (20.7) |
40–49 | 87,707 (19.1) | 348,335 (19.2) |
50–59 | 84,454 (18.4) | 327,230 (18.0) |
60–69 | 41.841 (9.1) | 153,227 (8.4) |
≥ 70 | 36,028 (7.9) | 134,209 (7.4) |
Ethnicity, n (%) | ||
White | 295,067 (64.4) | 1,079,656 (59.4) |
South Asian | 55,792 (12.2) | 192,600 (10.6) |
Black | 19,226 (4.2) | 86,040 (4.7) |
Mixed ethnicity | 7066 (1.5) | 34,134 (1.9) |
Other | 6614 (1.4) | 33,873 (1.9) |
Missing | 74,382 (16.2) | 392,626 (21.6) |
BMI | ||
Mean (SD) | 27.6 (6.3) | 26.8 (6.1) |
Median (IQR) | 26.7 (23.3–30.9) | 25.8 (22.5–29.8) |
BMI categories, n (%) | ||
Underweight (< 18.5 kg/m2) | 12,038 (2.6) | 59,644 (3.3) |
Normal weight (18.5–25 kg/m2) | 136,480 (29.8) | 594,657 (32.7) |
Overweight (25–30 kg/m2) | 131,076 (28.6) | 473,031 (26.0) |
Obese (> 30 kg/m2) | 116,836 (25.5) | 366,198 (20.1) |
Missing | 61,717 (13.5) | 325,379 (17.9) |
Smoking status, n (%) | ||
Never smoked | 168,415 (36.8) | 657,775 (36.2) |
Ex-smoker | 167,507 (36.6) | 548,695 (30.2) |
Current smoker | 101,351 (22.1) | 482,322 (26.5) |
Missing | 20,874 (4.6) | 130,137 (7.2) |
Exposure to selected infection, n (%) | ||
All infections | 2354 (0.5) | 9098 (0.5) |
EBV | 153 (0.0) | 579 (0.0) |
CMV | 123 (0.0) | 327 (0.0) |
HHV-6 | 0 (0.0) | 4 (0.0) |
HTLV-1 | 0 (0.0) | 10 (0.0) |
Hepatitis C virus | 784 (0.2) | 4161 (0.2) |
Influenza A virus | 968 (0.2) | 2911 (0.2) |
Parvovirus B19 | 282 (0.1) | 947 (0.1) |
Exposure to selected medication, n (%) | ||
All medications | 821 (0.2) | 2552 (0.1) |
Procainamide | 0 (0.00) | 2 (0.0) |
Hydralazine | 218 (0.1) | 753 (0.0) |
Quinidine | 26 (0.0) | 92 (0.0) |
Isoniazid | 581 (0.1) | 1724 (0.1) |
Primary analysis
Outcome | Exposed cohort (n = 458,147) | Unexposed cohort (n = 1,818,929) |
---|---|---|
Outcome events, no. (%) | 696 (0.15) | 2230 (0.12) |
Person-years of follow-up | 151,569 | 611,211 |
Crude incidence rate per 1000 person-years | 4.59 | 3.65 |
Median follow-up, years (IQR) | 0.29 (0.24–0.42) | 0.29 (0.24–0.42) |
Crude HR (95% CI) | 1.26 (1.16–1.37) | |
Adjusteda HR (95% CI) | 1.22 (1.12–1.33) |
Secondary analysis
Outcome | Exposed cohort | Unexposed cohort |
---|---|---|
Autoimmune thyroiditis | ||
Outcome events | N < 5 | 18 |
Crude incidence rate per 1000 person-years | 0.020 | 0.029 |
Crude HR (95% CI) | 0.67(0.20–2.27) | |
Adjusted HR (95% CI) | 0.63 (0.19–2.15) | |
Coeliac disease | ||
Outcome events | 37 | 113 |
Crude incidence rate per 1000 person-years | 0.24 | 0.18 |
Crude HR (95% CI) | 1.32 (0.91–1.92) | |
Adjusted HR (95% CI) | 1.30 (0.90–1.89) | |
Inflammatory bowel disease | ||
Outcome events | 276 | 817 |
Crude incidence rate per 1000 person-years | 0.18 | 0.13 |
Crude HR (95% CI) | 1.37 (1.19–1.57) | |
Adjusted HR (95% CI) | 1.36 (1.18–1.56) | |
Myasthenia gravis | ||
Outcome events | 5 | 21 |
Crude incidence rate per 1000 person-years | 0.033 | 0.034 |
Crude HR (95% CI) | 0.96 (0.36–2.55) | |
Adjusted HR (95% CI) | 0.92 (0.35–2.45) | |
Pernicious anaemia | ||
Outcome events, | 17 | 50 |
Crude incidence rate per 1000 person-years | 0.11 | 0.082 |
Crude HR (95% CI) | 1.37 (0.79–2.38) | |
Adjusted HR (95% CI) | 1.34 (0.77–2.32) | |
Psoriasis | ||
Outcome events | 223 | 743 |
Crude incidence rate per 1000 person-years | 1.47 | 1.22 |
Crude HR (95% CI) | 1.21 (1.04–1.41) | |
Adjusted HR (95% CI) | 1.23 (1.05–1.42) | |
Rheumatoid arthritis | ||
Outcome events | 66 | 248 |
Crude incidence rate per 1000 person-years | 0.44 | 0.41 |
Crude HR (95% CI) | 1.08 (0.82–1.41) | |
Adjusted HR (95% CI) | 1.06 (0.81–1.40) | |
Sjogren’s syndrome | ||
Outcome events | N < 5 | 23 |
Crude incidence rate per 1000 person-years | 0.00066 | 0.038 |
Crude HR (95% CI) | 0.18 (0.02–1.31) | |
Adjusted HR (95% CI) | 0.17 (0.02–1.27) | |
Systemic lupus erythematosus | ||
Outcome events, no. (%a) | 10 | 39 |
Crude incidence rate per 1000 person-years | 0.066 | 0.064 |
Crude HR (95% CI) | 1.03 (0.51–2.06) | |
Adjusted HR (95% CI) | 1.02 (0.51–2.05) | |
Type 1 diabetes mellitus | ||
Outcome events | 42 | 106 |
Crude incidence rate per 1000 person-years | 0.28 | 0.17 |
Crude HR (95% CI) | 1.60 (1.12–2.29) | |
Adjusted HR (95% CI) | 1.56 (1.09–2.23) | |
Vitiligo | ||
Outcome events | 19 | 60 |
Crude incidence rate per 1000 person-years | 0.13 | 0.098 |
Crude HR (95% CI) | 1.28 (0.76–2.14) | |
Adjusted HR (95% CI) | 1.28 (0.77–2.15) |