Table 1.

The plausible effects of diabetes mellitus (DM) on tuberculosis (TB) natural history and treatment outcomes.

Effect	Description	Statistical measure of effect as incorporated in the model	Expected range based on available evidence	Sources
Effects of DM on TB’s natural history (TB infection and/or TB disease)
Effect 1-Susceptibility	DM increases the susceptibility to TB infection	Hazard ratio	≥1	36– 40
Effect 2-Fast progression	DM increases the proportion of TB infections entering latent-fast state as opposed to latent-slow state	Proportion ratio	≥1	5,8,10,42–48
Effect 3-Reactivation	DM increases the rate of developing TB disease among those with latent TB infection	Rate ratio	≥1	5, 8, 10, 42– 48
Effect 4-Latent reinfection	DM increases the susceptibility to TB reinfection among those with latent-slow TB infection	Hazard ratio	≥1	5, 8, 10, 42– 48
Effect 5-Smear positivity	DM increases the proportion of new PTB# disease cases progressing to SP-PTB* as opposed to SN-PTB$	Proportion ratio	≥1	51– 60
Effect 6-Disease infectiousness	DM increases the infectiousness of PTB (SP-PTB and SN-PTB) for both untreated and treated TB disease cases	Factor ratio	≥1	51, 54, 61, 62
Effect 7-TB mortality	DM increases the hazard of TB-related mortality for both untreated and treated TB disease cases	Hazard ratio	≥1	12, 52, 53, 60, 61, 63
Effects of DM on TB treatment outcomes
Effect 8-Treatment failure	DM reduces the proportion of successful treatment (through increased risk of treatment failure and MDR-TB¥)	Proportion ratio	≥1	12, 57, 64
Effect 9-Recovery	DM reduces the rate of TB recovery (i.e. prolongs the recovery time) for those who recover naturally or due to treatment	Rate ratio	≥1	51, 54, 55, 64– 67
Effect 10-Cured reinfection	DM increases the susceptibility to TB reinfection among those treated or recovered from TB disease	Hazard ratio	≥1	12, 64

^#PTB: Pulmonary TB; *SP-PTB: smear-positive pulmonary TB; ^$SN-PTB: smear-negative pulmonary TB; ^¥MDR-TB: multi-drug resistant TB.