Variability in prescription drug expenditures explained by adjusted clinical groups (ACG) case-mix: a cross-sectional study of patient electronic records in primary care

BACKGROUND

In view of rapidly increasing prescription costs, case-mix adjustment should be considered for effective control of costs. We have estimated the variability in pharmacy costs explained by ACG in centers using patient electronic records, profiled centers and physicians and analyzed the correlation between cost and quality of prescription.

METHODS

We analyzed 65,630 patient records attending five primary care centers in Spain during 2005. Variables explored were age, gender, registered diagnosed episodes of care during 2005, total cost of prescriptions, physician and center. One ACG was assigned to each patient with ACG case-mix software version 7.1. In a two-part model, logistic regression was used to explain the incurrence of drug expenditure at the first stage and a linear mixed model that considered the multilevel structure of data modeled the cost, conditional upon incurring any expense. Risk and efficiency indexes in pharmacy cost adjusted for ACG were obtained for centers and physicians. Spearman rank correlation between physician expenditure, adjusted for ACG, and a prescription quality index was also obtained. Pediatric and adult data were analyzed separately.

RESULTS

No prescription was recorded for 13% of adults and 39.6% of children. The proportion of variance of the incurrence of expenditure explained by ACGs was 0.29 in adults and 0.21 in children. For adults with prescriptions, the variance of cost explained by ACGs was 35.4%, by physician-center was 1.8% and age 10.5% (residual 52.3%). For children, ACGs explained 22.4% of cost and physician-center 10.9% (residual 66.7%). Center efficiency index for adults ranged 0.58 to 1.22 and for children 0.32 to 2.36. Spearman correlation between expenditure and prescription quality index was -0.36 in family physicians (p = 0.019, N = 41) and -0.52 in pediatricians (p = 0.08, N = 12).

CONCLUSION

In our setting, ACG is the variable studied that explains more variability in pharmacy cost in adults compared to physician and center. In children there is greater variability among physicians and centers not related to case-mix. In our sites, ACG is useful to profile physicians and centers using electronic records in real practical conditions. Physicians with lower pharmaceutical expenditure have higher scores for a prescription quality index.

[Acceptance of generic prescribing in general practice: effect of patient education and reference prices]

AIMS

To assess patient acceptance of the substitution of brand-name drugs for generic equivalents in the context of repeat prescriptions for chronic diseases.

METHODS

A prospective multicenter study of drug use was performed. Of the 31 centers included in the study, 8 were randomized to the intervention group and 23 to the control group. For 1 year, patients in the intervention group who visited the center to collect repeat prescriptions received verbal and written information on the advantages and disadvantages of generic and brand name drugs. Data on the number of patients taking brand-name drugs for which generic equivalents were available, as well as the reasons and variables related to refusal of generic drugs (age, gender, education, primary care centre, general practitioner, type of drug and total number of repeat prescriptions) were collected. The percentage of generic drugs among the total number of drugs prescribed was calculated at 2-monthly intervals.

RESULTS

A total of 98.9% of the 4620 patients in the intervention group agreed to change to a generic formulation. The percentage of patients accepting generic drugs was significantly associated with the primary care centre, the class of drug, doctors' influence, and patient satisfaction with the drug. Generic prescriptions represented 5.9% in the intervention practices compared with 2.8% in controls. After the intervention, and before the application of reference prices, the percentages were 6.7% and 3.9%, respectively. Immediately after application of the reference prices, the percentages were 8.6% and 6.3%, respectively.

CONCLUSIONS

Direct patient education is an effective strategy in increasing the prescription of generic equivalents. General practitioners' motivation and knowledge of generic drugs influenced their use. The application of reference prices increased the use of generic equivalents.