Categorisation of continuous risk factors in epidemiological publications: a survey of current practice

Table 6 Example of categorisation from the survey (4).

	No. of cases	No. of controls	Odds Ratio	95% CI
No bereavement	2589	12722	Referent
Time since bereavement (yrs)
≤ 5	24	180	0.6	0.4, 1.0
6-10	18	116	0.8	0.5, 1.2
11-15	8	107	0.4	0.2, 0.8
16-20	11	80	0.7	0.4, 1.3
≥ 21	44	265	0.8	0.6, 1.1

Risk of amyotrophic lateral sclerosis (ALS) for bereaved parents by years since bereavement [23].
Reason for inclusion as an example. Example of a 'never' category, reference is 'never' category.