Make a list of all your stock transactions to date, categorizing them according to whether they are long-term or short-term, gainers or losers.
Since only a few remaining pictures are dated, categorizing them is difficult.
Exposure to drugs was collected before the start date and categorized as follows: current use, when the supply of the most recent prescription lasted until the start date or ended in the 90 days before the start date; recent use, when supply of the most recent prescription ended more than 90 days before the start date; and non-use, when there was no recorded use any time before the start date.
Postcodes classified as 'Flooded (known date)' were categorized by application of three rules: Rule 1.
Physician visits in the 2 years before the index date were categorized in tertiles as ≤12 visits (low), 13 24 visits (medium), and ≥25 visits (high).
The calculated number of FRIDs during the 90-day period prior to the index date was categorized into two groups: 0 vs. ≥1.
It was based on ICD diagnoses captured in hospital records and physician billing claims for the one-year period prior to the study index date and categorized as 0, 1 to 2, and 3 or more.
Hence, more information, and consequently less non-differential misclassification, is obtained with the introduction of extra determinants x2, and x3, where the cumulative continuous exposure to thiazides at the index date is categorized as: x1 = 1 through 42 days; x2 = 42 through 365 days; x3 > 365 days.
In the previously mentioned study, additional categorical determinants were created as extra determinants x4, x5, and x6 where the number of days since last intake of thiazides, counting back from the index date, was categorized as: x4 = 1 through 60 days; x5 = 61 through 365 days; and x6 > 365 days.
