To avoid interference with AFP levels, patients who began or stopped antiviral therapy during the 18 months preceding the HCC occurrence or the enrollment (controls) were excluded.
Epidemiologic challenges addressed in the design of PERCH included eligibility criteria for case and control enrollment, matching criteria, the sampling strategy for both cases and controls, where to identify controls, and whether to enroll controls with upper respiratory tract infection (URTI) or nonsevere pneumonia.
The enrollment of controlling size and homogeneity of the silver embedded silica particles by the conventional methods is tedious but from the spray technique nanometer to micrometer sized particles can be effectively controlled and ensures its viable applications in various fields.
Patients with previous history of ARDS and previous enrollment as controls were excluded.
Factors examined as potential confounders or effect modifiers included age (at breast cancer diagnosis for cases, at time of study enrollment for controls), age at first birth, number of children, birth of a son, history of breastfeeding, miscarriage, abortion, oral contraceptive use, smoking status, age at menarche and number of cell equivalents tested for detection of FMc.
Reference age is defined as age at diagnosis for cases and age at enrollment for controls.
* Age at diagnosis for cases and at study enrollment for controls.
Enrollment was controlled so that approximately 80%and20%0% of patients had face and scalp AK, respectively.
Each day during the enrollment period, controls were numbered in the order in which they were admitted and identified.
The duration of enrollment of controls was limited to 6 months because of problems of availability of the healthcare staff.
The majority of the women were pre-menopausal at the time of cancer diagnosis (62%) or enrollment for controls (57%).
