AUDIT OF PREVENTIVE ACTIVITIES IN 16 INNER LONDON PRACTICES USING A VALIDATED MEASURE OF PATIENT POPULATION, THE ACTIVE PATIENT DENOMINATOR

Background. Reliable comparison of the results of audit between genera l practices and over time requires standard definitions of numerators and denominators. This is particularly relevant in areas of high popul ation turnover and practice list inflation. Without simple validation to remove supernumeraries, population coverage and professional activi ty may be underestimated. Aim. This audit study aimed to define a stan dard denominator, the 'active patient' denominator, to enable comparis on of professional activity and population coverage for preventive act ivities between general practices and over time. It also aimed to docu ment the extent to which computers were used for recording such activi ties. Method. A random sample of people in the age group 30-64 years w as drawn from the computerized general practice registers of the 16 in ner London general practices that participated in the 'healthy eastend ers project'. A validation procedure excluded those patients who were likely to have died or moved away, or who for administrative reasons w ere unable to contribute to the numerator; this allowed the creation o f the active patient denominator. An audit of preventive activities wi th numerators drawn from both paper and computerized medical records w as carried out and results were presented so that practices could comp are their results with those of their peers and over rime. Results. Of the original sample of 2331 people, 25% (practice range 13%-37%) were excluded as a result of the validation procedure. A denominator based on the complete, unexpurgated practice register rather than the valid ated active patient denominator would have reduced the proportion of p eople with blood pressure recorded within the preceding five years fro m 77% to 61%, recording of smoking status from 68% to 53% and recordin g of cervical smears from 80% to 66%. Only 53% of the last recordings, within the preceding five years, of blood pressure and only 54% of th ose of smoking status were recorded on the practice computer. In contr ast, 82% of recorded cervical smears were recorded on computer. Conclu sion. The active patient denominator produces a more accurate estimate of population coverage and professional activity, both of which are u nderestimated by the complete, unexpurgated practice register. A stand ard definition of the denominator also allows comparisons to be made b etween practices and over time. As only half of the recordings of some preventive activities were recorded on computer, it is doubtful wheth er it is advisable to rely on computers for audit where paper records are also maintained.