Survival status and date were assessed through municipal civil registries in 2010 and were available for 99% of all patients.
Changes between the acidic to the calcareous soil within each treatment, origin and date were assessed in a similar way.
Comorbidities present in the 3 years prior to the index date were assessed using physician claims and hospitalization data together with validated algorithms for the variables listed in Table 1 (17– 20).
Increased risk of infant hospitalization for bronchiolitis was significantly associated with subchronic and chronic exposures to PM in Los Angeles (Karr et al. 2007), where exposures in the month prior to hospitalization (subchronic) and mean lifetime exposure (chronic) referenced to the case diagnosis date were assessed on the basis of data derived from the California Air Resources Board.
The best catalysts to date are assessed with a view to their composition, e.g., alloys, and regarding the role of the support material and solvent used.
The proportion of exacerbation cases prescribed an antibiotic on the index date was assessed by GP practice.
Association with survival, calculated from the first Mayo visit date to the last follow up or death date, was assessed using Cox Proportional Hazards regression.
Diet in the year prior to the reference date was assessed with the National Cancer Institute's self-administered Diet History Questionnaire, previously adapted for use in Canada [ 36].
Breeding date was assessed as the first day of spawn observation and local temperature recorded for five, paired high- and low-altitude R. temporaria breeding sites in Scotland.
Viability of the pollen at each date was assessed by incubating vials for 4 h at room temperature under light conditions and continuous shaking (Hortynski and Zebrowska 1991) before staining with 1.0 % acetocarmine.
While it has, to date, been assessed with only one validation study, 15 it should be at least as accurate as the single channel nasal flow to predict the AHI since, according to current rules, a hypopnoea cannot be scored without an oxygen desaturation.
