Ethical approval was obtained from the NHS Research Ethics Committee and UEL Ethics Committee prior to the study (Reference: 10/H0707/88; date: 20/09/2010).
We chose January 1st, 2011, the middle of the study period, as reference date for the population data.
Because of the longer time needed to enroll birth certificate controls in the main study, the time between the reference date and dust collection was shorter for cases [median years, interquartile range (IQR): 0.92 (0.74–1.26] than for controls [1.66 (1.26–2.24)].
a Adjusted for sex, age at reference date, race, study center, education level, history of hypertension, smoking status, BMI (5 years prior to interview) and family history of cancer.
Because of the longer time period involved in identifying, enrolling, and interviewing birth certificate controls in the main study, the time between the reference date and dust collection was less for cases {median [interquartile range (IQR)] years: cases, 0.96 (0.76–1.38); controls, 1.55 (1.24–1.97)}.
The estimated ICERs from the screening models can be translated into £-sterling at current prices, using both the purchasing power parity exchange rate at the reference date of each study and the National Health Service (NHS) HCHS Pay and Price Index.
We classified cases according to their status as of the date of their first skin cancer diagnosed during the study period and controls as of their reference date.
The exposure period for these studies was habitual regular drinking at the reference date (HOP) or the time period approximately five years before the reference date (CON, GER, NCO and POL).
To address the timing of alcohol exposure, women were categorized as a lifetime abstainer, former drinker (in our study, these women quit drinking 2 58 years before reference date; median 17 years), or current drinker as of the reference date.
We defined the study reference period as the 30 days after the index patient's date of GAS culture.
A structured questionnaire designed specifically for this study was administered during the in-person interview, obtaining data up to the reference date.
