Table 5.
Potential risk factors for disease severity
| Potential risk factor | Study supports risk | Study does not support risk or is neutral |
|---|---|---|
| Sex |
Odds ratio for severe disease 3.68 for men compared to women (multivariable regression) [36] Odds ratio for invasive mechanical ventilation 2.83 for men compared to women (multivariable regression) [37] Females less likely to be admitted to ICU, require mechanical ventilation, or die; odds ratio 0.61 (multivariable logistic regression) [31] |
Sex distribution similar in severe and non-severe disease (descriptive) [30, 49] Sex distribution similar in severe and non-severe disease (statistical test) [23, 26, 28, 29, 32, 34, 38, 39, 41–44, 48–50] Sex distribution similar in severe and non-severe disease (multivariable regression) [19, 20] |
| Age |
Averagea 61 years severe disease, 45 otherwise (statistical test) [38] Averagea 61 years severe disease, 52 years moderate disease (statistical test) [23] Averagea 56 years severe disease, 44 years mild disease (statistical test) [39] Median 67 years acute respiratory distress syndrome, 52 severe, 45 mild (statistical test) [42] Median 64 years severe patients, 52 years otherwise (statistical test) [48] Mean 61 years severe, otherwise 40 (statistical test) [50] Median 71 years SpO2 < 90%, 37 years SpO2 ≥ 90% (statistical test) [43] Median 66 years patients in ICU, 51 otherwise (statistical test) [41] Median 54 years patients in ICU, 41 otherwise (statistical test) [26] 65 years and over 3.26 times the hazard rate of ARDS than those under 65 (univariable regression) [44] Age associated with ICU admission, odds ratio 1.06 but unclear for what categorisation of age (multivariable regression) [20] |
Distribution of age did not differ by disease severity (descriptive) [30, 34, 49] Distribution of age did not differ by disease severity (statistical test) [28, 29, 32] Confidence interval for effect of age (categorisation unclear) crosses the null (multivariable regression) [37] |
|
Mean 56 years severe disease, 45 years mild disease; odds ratio 1.06 but unclear categorisation of age (multivariable regression) [36] Mean 63 years severe disease, 41 years mild disease; odds ratio 1.08 but unclear categorisation of age (multivariable regression) [19] Older individuals more likely to be admitted to ICU, require mechanical ventilation, or die; odds ratio 1.05, categories of age unclear (multivariable logistic regression) [31] |
||
| Ethnicity | 76.3% of individuals receiving basic respiratory support were White versus 65.6% receiving advanced respiratory support; Asian and Black ethnicities appear most at risk of severe disease (England, Northern Ireland and Wales; descriptive) [30] | Distribution of disease severity similar across ethnic groups (Chinese, Malay, Indian, other – with small numbers in groups other than Chinese; study in Singapore; descriptive) [26] |
| Deprivation | Distribution across deprivation categories similar (descriptive) [30] | |
| Pregnancy | Distribution in pregnant and non-pregnant individuals similar across disease severity (descriptive) [30] | |
| Smoking | 100% of current smokers had severe disease, but only six individuals smoked [50] |
Distribution in current and non-current smokers similar across disease severity (descriptive), only three individuals smoked [39] Distribution in current and non-current smokers similar across disease severity (statistical test); small numbers who smoked [29] Distribution in historical/current and non-smokers similar across disease severity (statistical test) [36, 48] |
| Body mass index |
≥35 kg/m2 risk factor versus < 25 kg/m2 for invasive mechanical ventilation; odds ratio 7.36. Results for other strata cross the null (multivariable regression) [37] Increasing body mass index increased risk; odds ratio 1.17 (categorisation unclear) [19] |
Distribution of disease severity similar across body mass index categories (descriptive) [30] |
| Any/other comorbidity | Presence of comorbidity more common among those with severe disease (statistical test) [39, 41, 48, 50] |
Distribution with and without condition similar across disease severity (statistical test) [23, 29, 36] Distribution with and without comorbidities not otherwise considered in the study similar across disease severity (statistical test) [50] Distribution with and without condition similar across disease severity (multivariable regression) [20] |
| Cardiovascular disease/chronic heart disease/coronary heart disease |
Presence of comorbidity more common among those with severe disease (descriptive) [39] Presence of comorbidity more common among those with severe disease (statistical test) [19, 36, 41, 43, 50] |
Distribution with and without condition similar across disease severity (descriptive) [30, 44] Distribution with and without condition similar across disease severity (statistical test) [29, 48] |
| Hypertension |
Presence of comorbidity more common among those with severe disease (statistical test) [41, 43, 50] Hazard ratio of ARDS 1.82 in those with the condition versus those without (univariable regression) [44] Odds ratio of severe disease 2.71 in those with the condition versus those without (multivariable regression) [36] Odds ratio of being admitted to ICU, require mechanical ventilation, or die 1.89 in those with the condition versus those without (multivariable regression) [31] |
Distribution with and without condition similar across disease severity (descriptive) [39] Distribution with and without condition similar across disease severity (statistical test); one study with small numbers with the condition [23, 29, 42, 48] Confidence interval in presence and absence of condition crosses the null (multivariable regression) [19] Confidence interval in presence and absence of condition crosses the null (multivariable regression, result borderline) [37] |
| Diabetes |
Presence of comorbidity more common among those with severe disease (descriptive) [39] Presence of comorbidity more common among those with severe disease (statistical test) [19, 36, 41, 43, 50] Hazard ratio of ARDS 2.34 in those with the condition versus those without (univariable regression) [44] Odds ratio of being admitted to ICU, require mechanical ventilation, or die 2.21 in those with the condition versus those without (multivariable regression) [31] |
Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [23] Distribution with and without condition similar across disease severity (statistical test) [29, 48] Distribution with and without condition similar across disease severity (statistical test, borderline result) [42] Confidence interval in presence and absence of condition crosses the null (multivariable regression) [37] |
| Respiratory/pulmonary disease | Distribution with and without condition similar across disease severity (descriptive) [30, 39] | |
| Asthma | Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [43] | |
| Chronic obstructive pulmonary disease (COPD) |
Presence of comorbidity more common among those with severe disease (descriptive); small numbers with condition [39] Presence of comorbidity more common among those with severe disease (statistical test); both studies have small numbers with the condition [41, 50] Odds ratio of being admitted to ICU, require mechanical ventilation, or die 3.40 in those with the condition versus those without (multivariable regression) [31] |
Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [29, 43, 48] |
| Pulmonary tuberculosis | Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [48] | |
| Malignancy |
Presence of comorbidity more common among those with severe disease (statistical test); small numbers with condition [39] Presence of comorbidity more common among those with severe disease (statistical test) [36, 42, 50] Presence of comorbidity more common among those with severe disease (multivariable analysis) [31] |
Distribution with and without condition similar across disease severity (descriptive) [30] Distribution with and without condition similar across disease severity (statistical test) [41] Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [19, 29, 43] |
| Cerebrovascular disease | Presence of comorbidity more common among those with severe disease (statistical test) [41] | |
| Arrhythmia | Distribution with and without condition similar across disease severity (statistical test); small numbers with the condition [48] | |
| Cerebral infarction | Distribution with and without condition similar across disease severity (statistical test) [42] | |
| Stroke | Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [48] | |
| Aorta sclerosis | Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [48] | |
| Chronic kidney disease/renal issues | Presence of comorbidity more common among those with severe disease (statistical test) [42] |
Distribution with and without condition similar across disease severity (descriptive) [30] Distribution with and without condition similar across disease severity (statistical test); small numbers with the condition [41] |
| Chronic renal disease/insufficiency | Distribution with and without condition similar across disease severity (statistical test); one study has small numbers of patients with the condition [36, 48] | |
| Chronic liver disease |
Distribution with and without condition similar across disease severity (descriptive), sometimes small numbers with condition [19, 30, 39] Distribution with and without condition similar across disease severity (statistical test) [36, 41] Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [29, 50] |
|
| Fatty liver and abnormal liver function | Distribution with and without condition similar across disease severity (statistical test) [48] | |
| Hyperlipidaemia | Distribution with and without condition similar across disease severity (statistical test) [48] | |
| Dyslipidemia | Confidence interval in presence and absence of condition crosses the null (multivariable regression) [37] | |
| Chronic gastritis/gastric ulcer | Distribution with and without condition similar across disease severity (statistical test) [48] | |
| Cholelithiasis | Distribution with and without condition similar across disease severity (statistical test) [48] | |
| Urolithiasis | Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [48] | |
| Thyroid diseases | Distribution with and without condition similar across disease severity (statistical test); small numbers with the condition [48] | |
| Electrolyte imbalance | Presence of comorbidity more common among those with severe disease (statistical test); small numbers with condition [48] | |
| Agglomerative disease | Distribution with and without condition similar across disease severity (descriptive); small numbers with the condition [39] | |
| Immunocompromised | Distribution with and without condition similar across disease severity (descriptive) [30] | |
| Chronic hepatitis | Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [43] | |
| HIV | Distribution with and without condition similar across disease severity (statistical test); small numbers with condition [41] | |
| Living without assistance | Distribution with and without condition similar across disease severity (descriptive) [30] |
One study included death in a combined measure of disease severity [31]. aUnclear as to whether mean, median or mode. ARDS acute respiratory distress syndrome, ICU intensive care unit, SpO2 oxygen saturation