| Advantage | Disadvantage | |
| Measured directly | Confirm drug use and dose | Misleading if drug taken prior to testing |
| Biochemical* | Less subject to bias | Limited intervals that can be monitored |
| Little information regarding use over time | ||
| Insensitive to inhaled drug | ||
| Limited availability and costly | ||
| Measured indirectly | ||
| Physician’s estimate and patient self-report | Easy to obtain | Unreliable |
| Pharmacy records filling prescription | Confirm filling prescription | Need centralised pharmacy records |
| Pharmacy database can be incomplete | ||
| Pill count or inhaler weighing† | Easy to obtain | Overestimate compliance |
| Correlate well with other methods of measurement | ||
| Therapeutic outcome | Easy to obtain | Clinical outcomes can depend on other factors |
| Electronic monitoring† | Helps explain how medications were taken | Expensive and not adapted to all inhalation devices |
*Measurement includes blood levels or urinary excretion of the medication, a metabolite or a marker.
†It does not verify that the medicine was ingested.