When there is little to choose between different drugs available for the same purpose, as in the case of the anti-inflammatory analgesic drugs discussed in the preceding article, it is reasonable to make the choice on grounds of cost. It can however be difficult to construct a meaningful cost comparison for the drugs in a particular therapeutic group. One obvious problem is that of dosage, for it is not clear which dose in a wide range should be chosen for the comparison. Perhaps the most appropriate dosage is that most commonly used (the modal dosage) in long-term maintenance therapy. The modal dose could be derived from an analysis of prescriptions, or estimated approximately from clinical trial reports, or from a consensus view of clinicians with experience of the drug. But provided the dose used in a comparison is clearly stated the result should not mislead anyone, even if the dose is chosen arbitrarily. A second problem is the difference in drug costs in hospitals and in retail pharmacy. Hospital prices are generally not published, and vary between different hospitals, whereas retail pharmacy prices are published and uniform. Some manufacturers have deliberately charged hospitals low prices for a drug and retail pharmacists high prices, presumably to increase use of the drug in hospitals which are more cost-conscious, and which also influence prescribing by family doctors in their catchment area. As long as such multiple pricing continues it seems more practical to base comparisons on retail costs. Thirdly, should non-drug costs be included, such as the pharmacist’s fee, on-cost allowance, and container allowance; and should the sum collected as prescription charge be deducted? Since on the whole these items are constant, they do not affect the essentials of comparisons and they may just as well be omitted.
Generalized Mathematical Expressions for Various Repayment Plans and Long Term Cost Comparison
