Diffusion of innovation II: Formulary acceptance rates of new drugs in teaching and non-teaching British Columbia hospitals--a drug development perspective.

Diffusion theory was used to examine differences in adoption rates of new drugs by British Columbia teaching and non-teaching hospitals. Surveys were mailed in September 1990 to 41 hospital pharmacies (response rate = 88%), requesting hospital pharmacy directors to provide formulary inclusion dates of 29 study drugs marketed between July 1987 and March 1990. Of the 36 initial responses, 31 were suitable for further analysis and these were surveyed again in April 1993 (response rate = 100%) as to the formulary status of drugs not initially approved. The second survey ensured that all study drugs would have at least 36 months on the Canadian market when determining formulary acceptance times. Of the 29 study drugs, six were not approved for use in any of the 31 study hospitals. The six teaching hospitals had a median formulary approval time of 8.0 months compared to 12.8 months in the 25 non-teaching hospitals for the 23 study drugs. Although 21 of 23 study drugs were approved for use earlier in teaching hospitals than non-teaching hospitals, only alfentanil was found to be adopted significantly earlier (U = 11, n1 = 5, n2 = 19, alpha = 0.05). Variations in formulary approval times for new drugs have a bearing on patient care, Pharmacy and Therapeutics Committees, hospital budgets, and pharmaceutical firm revenues.

Diffusion of innovation I: Formulary acceptance rates of new drugs in teaching and non-teaching British Columbia hospitals--a hospital pharmacy perspective.

Lag times in the diffusion of new drugs in the hospital setting have both patient care and pharmaceutical industry implications. This two-part series uses diffusion theory to examine differences in the adoption rates of new drugs in British Columbia teaching and non-teaching hospitals. Formulary addition of a new drug by a hospital's Pharmacy and Therapeutics Committee was considered the adoption indicator. Time for adoption was defined as the difference between a drug's Canadian market approval date and the date of formulary addition. Surveys were mailed in September 1990 to 41 hospital pharmacies (response rate = 88%), asking respondents to provide formulary inclusion dates of 29 drugs marketed between July 1987 and March 1990. A significant difference (Mann-Whitney U Test, p < 0.0358) in median adoption time was observed between the six teaching and 25 non-teaching study hospitals, with the former adopting a new drug in 7.5 months versus the latter adopting a new drug in 12.1 months.

Exponential smoothing method for forecasting drug expenditures.

A model for forecasting a hospital pharmacy drug budget is described, and its results in 10 hospital pharmacy departments are evaluated. A model for forecasting inpatient drug expenditures was developed based on the method of exponential smoothing. Exponential smoothing predicts a value based on the forecast for the prior period, with adjustment for the error of that forecast. Recent data are weighted more heavily than older data; as data become older, weights decline exponentially. The model incorporates changes in workload in addition to drug expenditure data. The variable used for workload can vary from one hospital to another, depending on the statistics that are available. The model was designed to be more accurate than current methods, easy and quick to use, and usable with a minimal knowledge of statistics and forecasting theory. The model was tested on fiscal 1988-1992 drug budget data from 10 British Columbia hospital pharmacy departments. Four departments had insufficient data; of the remaining six, the forecasting model performed better than the hospitals' current methods in four departments. The mean absolute deviation between budgeted (by current methods) and actual drug expenditures was 8.70% (range, 6.19-15.16%). The forecasting model yielded a mean absolute deviation of 5.93% (range, 3.13-7.66%). Better forecasts resulted when pharmacy medication-order volume was used as a workload variable, as compared with hospital inpatient days. An exponential smoothing model improved the accuracy of drug-budget forecasts in four of six pharmacy departments.