Unit conversion with the existing tasks

Hi, @mmcdermott @gkondas

I am looking to fit the tasks in different datasets to the following tasks:

"abnormal_lab/vital/hypotension/first_24h"
"abnormal_lab/blood_chemistry/metabolic_acidosis/first_24h"
"abnormal_lab/blood_chemistry/hyponatremia/first_24h"
"abnormal_lab/blood_chemistry/elevated_creatinine/first_24h"
"abnormal_lab/cbc/leukocytosis/first_24h"
"abnormal_lab/cbc/thrombocytopenia/first_24h"
"abnormal_lab/cbc/anemia/first_24h"

The issue is that several datasets report mmol/L instead of g/dL. Firstly, this is non-trivial, as we need to know the molecular mass (although we can use common conversions, such as those for hemoglobin).

Second: currently, the thresholds are in both the predicates.yaml and the task.yaml: see https://github.com/Medical-Event-Data-Standard/MEDS-DEV/blob/main/src/MEDS_DEV/tasks/abnormal_lab/blood_chemistry/elevated_creatinine/first_24h.yaml. I would think the preferred place to put them is in the predicates only, such that the unit can be dataset-agnostic. Is this a bug? Why is this redundancy here?

Start with src/MEDS_DEV/tasks/abnormal_lab/blood_chemistry/elevated_creatinine/first_24h.yaml and compare its thresholds with the predicates.yaml and task.yaml files mentioned in the issue. Trace how the existing tasks map measurements and units across datasets, including the listed abnormal-lab tasks. Done means the required unit conversions and the intended threshold location are established clearly enough to support dataset-agnostic task definitions.