Table 6.

Potential risk factors for mortality

Potential risk factor	Study supports risk	Study does not support risk or is neutral
Sex	Men more at risk (descriptive) [21]	Sex distribution similar amongst patients who died and survived (descriptive) [25, 35, 46, 47] Confidence interval for males versus females crosses the null (univariable regression) [44]
Age	Over 60 years particularly at risk (descriptive) [21] 8% case fatality ratio in 70–79 year olds and 14.8% in those over 80. Overall figure 2.3% (descriptive) [45] Median age in those who died 52 years, 65 years among survivors (descriptive) [46] Over 50 years of age particularly at risk- 1.3% died 50–59 years, 3.6% 60–69 years, 8.0% 70–79 years, 14.8% 80 years plus; less than 1% all other age groups (descriptive) [25] Risk begins to increase at approximately 50 years (statistical test, but graphical presentation) [35] Median age in those who died 68 years, among those who survived 55 (statistical test) [47] Over 61 years, increasing per 10 year age group (statistical test) [27] 65 years and older 6.17 the hazard rate of those under 65 (univariable regression) [44]
Smoking		Proportion of smokers similar among those who died versus those who did not (descriptive); one study had small numbers of smokers [21, 46] Distribution of current smokers similar among survivors and non-survivors (univariable regression analysis, not included in multivariable model) [51]
Pregnancy		Proportion of women who were pregnant similar amongst patients who died versus survived (descriptive) [21]
Any comorbidity	Presence of any comorbidity more common among those dying (descriptive) [21, 35, 46, 47, 51]
Hypertension	Presence of condition more common among those dying (descriptive) [3, 21, 25, 27] Presence of condition more common among those dying (statistical test) [47, 51]	Confidence interval for individuals with and without the condition crosses the null (univariable regression) [44]
Cardiovascular disease/chronic heart disease	Presence of condition more common among those dying (descriptive) [21, 25, 35, 45] Presence of condition more common among those dying (statistical test) [47, 51]	Distribution dying in presence and absence of comorbidity similar (descriptive), sometimes small numbers with the condition [44, 46]
Diabetes	Presence of condition more common among those dying (descriptive) [21, 25, 45, 46] Presence of condition more common among those dying (statistical test) [47, 51]	Confidence interval for individuals with and without the condition crosses the null (univariable regression) [44]
Chronic respiratory/lung disease (chronic obstructive lung disease)	Presence of condition more common among those dying (descriptive) [21, 45] Presence of condition more common among those dying (statistical test) [51]	Distribution dying in presence and absence of comorbidity similar (descriptive) [46]
Respiratory infectious disease	Presence of condition more common among those dying (descriptive) [25]
Malignancy	Presence of condition more common among those dying (descriptive) [3, 25]	Distribution dying in presence and absence of comorbidity similar (descriptive), sometimes small numbers with the condition [46, 47, 51]
Cerebral infarction/ cerebrovascular disease	Presence of condition more common among those dying (descriptive) [46]	Distribution dying in presence and absence of comorbidity similar (statistical test); small numbers with the condition [47]
Chronic gastritis		Distribution dying in presence and absence of comorbidity similar (statistical test); small numbers with the condition [47]
Chronic kidney disease	Presence of condition more common among those dying (statistical test); small numbers with the condition [51]
Dementia		Distribution dying in presence and absence of comorbidity similar (descriptive); small numbers with the condition [46]
Malnutrition		Distribution dying in presence and absence of comorbidity similar (descriptive); small numbers with the condition [46]
Hepatitis B virus infection		Distribution dying in presence and absence of comorbidity similar (descriptive) [21]