Analyzing the Relationship between Cohort and Case-Control Study Results Based on Model for Multiple Pathogenic Factors

Table 1

Frequency distribution of individuals in each group for a cross-sectional outcome.

Group	Disease (case)	Nondisease (control)	Risk	Odds
Exposed (factor)	a	b	Pe = a/(a + b)	Pe/(1 − Pe) = a/b
Nonexposed (control)	c	d	Pn = c/(c + d)	Pn/(1 − Pn) = c/d
Total	a + c	b + d	m = (a + c)/(a + b + c + d)	m/(1 − m) = (a + c)/(b + d)
Obs. frequencies	Pd = a/(a + c)	Pc = b/(b + d)	—	—

a, b, c, and d: frequency of individuals in each group; Pd and Pc: frequency of individuals with the related factor in the disease group and that in the nondisease group; Pe and Pn: incidence of the exposed group and that of the nonexposed group; m: incidence of a disease in the total population.