If the occurrence of rainfalls at different rain gauges within a given concurrent period is similar (e.g. high correlation of the numbers of rainy hours within a given one-day interval), these gauges are thus considered as members of a homogeneous group.
In addition, experiencing a suspected AEx in the concurrent period was found to be a significant risk factor for mortality, hospitalization, and subsequent suspected AEx.
AEx in the concurrent period was a consistent and strong risk factor across all these outcomes and was the strongest predictor of a subsequent AEx.
These conditions were again assessed during the concurrent period.
Information on the above clinical and HRU variables was also collected for the concurrent period to assess whether patients in different FVC% change groups had different characteristics in the concurrent period.
Overall, clinical characteristics and HRU were similar between FVC% change groups at initial IPF diagnosis and in the concurrent period.
The "concurrent period" was defined as the time from initial IPF diagnosis date to the FVC measurement closest to 6 months post-IPF diagnosis.
During the concurrent period, admission MRSA screening performed for all subjects in the study cohort within 24 hour of admission to the acute hospital.
For each model, the main independent variable of interest was the FVC% change group while the control variables consisted of physician's main practice setting, patient characteristics and symptoms at IPF diagnosis, smoking status, GAP index, suspected AEx in the concurrent period, and use of prednisone and azathioprine in the concurrent period.
Prospective (2002) drug expenditures were used instead of concurrent (2003) drug expenditures to avoid model endogeneity stemming from the possibility that registration for public drug benefits affected the level of drug spending households could afford in the concurrent period.
The incidence rate (IR) or risk of clinical and HRU outcomes was assessed using unadjusted regression analysis with FVC% change group as the only independent variable and was estimated at the per-patient-half-year level for the concurrent period and per-patient-year level for the subsequent period.
