Patients were required to have 12 months of continuous enrollment pre-index and post-index.
Logistic regression was used to model known CRPC status as a function of age, baseline comorbidity, baseline CRPC-specific costs, length of post-index enrollment, time from castration to index date, docetaxel use, evidence of bone X-ray or bone scan, number of PSA tests identified in the medical claims, and evidence of oncology or urology office visits.
As we required a period of 12 months of continuous enrollment following the index date for study inclusion, patients who died shortly following the index date would have been excluded from the study, and this may have impacted cost estimates.
A co- prevalent case was defined as someone who was diagnosed with TB within two months after enrollment of the index case [14].
Confounding factors examined included: age at enrollment, body mass index, development of hypertension, glomerular filtration rate, medication use, diet and alcohol intake and menopausal symptoms in women.
The follow-up period was stratified to define 3 cohorts of patients with 1, 2, or 3 years of continuous enrollment after the index hospitalization discharge date.
From our database, we identified as household case-patients their household members for whom TB was diagnosed within 24 months after enrollment of the index case-patient.
For the control cohort, since no pneumonia diagnosis was documented throughout the entire enrollment period, the index date was represented as one physician visit (randomly chosen if multiple visits existed) between January 1, 2005 and September 30 , 2011
Exclusion criteria included a history of nephrolithiasis, use of any prescription medications, over the counter medications, or dietary supplement within 14 days of enrollment, body mass index (BMI, weight (kg)/height (m)) ≥ 30 kg/m, or blood donation within 30 days of study enrollment.
We excluded members who had <2 years of continuous enrollment after their index date, had missing cost data in any of the 3 years, had long-term care costs at baseline, and were unmatched SS participants or control subjects, leaving 4,766 SS participants and 9,035 matched control subjects (14).
