Examination of the modification index revealed the presence of 18 large modification indices (>10).
The examination of effect modification showed that no factor significantly altered the results of the baseline models (data not shown).
Covariates with sufficient numbers in separate categories permitting some useful examination of effect modification were ventilation, literacy, and house construction.
Our examination of effect modification by BMI was restricted to men and estrogen-positive women (e.g. premenopausal women and postmenopausal women currently taking PMH).
For our examination of effect modification, odds ratios were adjusted for the matching factors of age and race in addition to following standard breast cancer risk factors, as described in the footnote of the last table.
Because case-crossover design allows for examination of effect modification at the level of the individual, rather than subgroup, we also modeled potential interactive effects between ozone, sex, and age.
This, plus the assessment of all second solid cancer sites in a single study, enabled the examination of effect modification by age and year of diagnosis, as well as estimation of the excess number and attributable proportion of second cancers that could be related to radiotherapy.
Examination of the modification indices suggested that the feeling fat subscale could be divided into two related subscales for our pregnant subgroup: (1) feeling fat – general (items 4, 8, 10, 25, 28, 35, and 38; numbers aligned with those reported in Ben-Tovim & Walker [ 19]), and (2) feeling fat – clothing specific (items 5, 14, 19, 42, and 44).
In the present study, we aimed to examine whether associations between ozone and daily mortality was modified by SES at the census tract level or by individual characteristics using a case-crossover design, which allows for the examination of effect modification at the individual level.
