Create the Drug Strengths Staged table from the Drug Strengths Processed table. Here, the fractional representations of each the value and the units are created if applicable. The final fields `value` and `unit` represent expressions as varchar that can be evaluated as numeric.
With the calculations staged in the Drug Strengths Staged table, it can be joined with the Drug Exposures table to calculate ingredient administrations for research on cumulative doses over time and other research use cases. It is important to note that some extended release formulations of common medications such as Tylenol have a a Drug Strength with a denominator of 24 hours, and calculations would require accommodation for the additional time dimension added in this table.
ds_stage( conn, conn_fun = "connectAthena()", write_schema = "patelm9", verbose = TRUE, render_sql = TRUE, render_only = FALSE )
The `value`` field is returned as character class expression for evaluation to limit rounding error in downstream calculations for non-whole number drug strengths. For example, the `value` for a drug with a numerator of 1 and denominator of 3 would have a staged_value of "1/3" rather than 0.3333. These values can be parsed into their numeric values by calling a function that parses and evaluates the expression such as the rlang's `parse_expr` function followed by a call to the base eval function.
Other drug strength functions:
ds_lookup_ucum(),
ds_process_drug_table(),
ds_process_map_table(),
ds_process(),
ds_stage_unit_fraction(),
ds_stage_value_fraction()
Other drug strength setup functions:
ds_process()