Table 2. Prevalence and prevalence ratios of isolated and combined exposure according to the occurrence of CMD, in health workers. State of Bahia, Brazil, 2012.

Variable	n	Prevalence of CMD (%)	PR	95%CI
Reference
Social support = 0, high demand = 0	228	17.0	1.00
Isolated exposures
Social support = 0, high demand = 1	325	24.0	1.41	1.02–1.94
Social support = 1, high demand = 0	140	17.9	1.05	0.67–1.62
Combined exposures
Social support = 1, high demand = 1	393	28.0	1.64	1.21–2.22
Expected combined effecta		24.9	1.46
RERIb			0.18
APc			0.10
Sd			1.39

CMD: Common mental disorders; PR: Prevalence ratio

^a Expected combined effect = P₀₁ - P₀₀ + P₁₀ - P₀₀ + P₀₀ / PR₀₁ - PR₀₀ + PR₁₀ - PR₀₀ + PR₀₀

^b Excess risk due to interaction (RERI) = PR₁₁ - PR₀₁ - PR₁₀ + 1

^c Attributable proportion due to interaction (AP) = (PR₁₁ - PR₀₁ - PR₁₀ + 1) / PR₁₁

^d Synergy index (S) = (PR₁₁ - 1) / (PR₀₁ + PR₁₀ - 2)