TYPES OF STUDIES TO OBTAIN QUALITY DATA ON A PATIENT LEVEL

3. TYPES OF STUDIES TO OBTAIN QUALITY DATA ON A PATIENT LEVEL

3.1. Prevalence or incidence studies?

3.1.1. Prevalence studies

The first evaluation studies were conducted at Harvard Medical School in the United States (Adler et al., 1971; Barrett et al., 1968) and in the United Kingdom (Cooke et al., 1983). The data collection took place during one day

210 Inge C. Gyssens method. This type of study is generally part of a larger study on the prevalence

of nosocomial infections. A large European epidemiologic study on nosocomial infections and antibiotic use in intensive care units (EPIIC) was conducted according to this method in 1993 (Vincent et al., 1995). Recently, an interven- tion programme on the quality of use of vancomycin used repeated point preva- lence studies before and after an intervention (Hamilton et al., 2000).

3.1.2. Incidence studies

The majority of audits have measured the incidence of antibiotic treatment courses. The data have been collected during longer periods: one month (Gyssens et al., 1996a; Moss et al., 1981; Swindell et al., 1983), two months (Durbin et al., 1981; Van Houten et al., 1998), three months (Parret et al., 1993), four months (Dunagan et al., 1991), five months (Fluckiger et al., 2000), and 2 years (Fowler et al., 1998; Quintiliani et al., 1987). These studies gave more precise data for determining the relationship between use and qual- ity, for example, excessive consumption in grams per 100 patient-days.

3.2. Simple audits or intervention audits?

The aim of an audit is to ultimately improve practices. In the spirit of a strategy of continuous improvement, studies that combine audits with inter- ventions are preferred above simple audits.

3.2.1. Simple audits “Case Review” or “Recommendations audit”

Simple audits are evaluations of quality of prescription without interven- tion. Often these studies are based on a selection of cases in a nonquantitative approach. Early reports were retrospective, for example, in the Netherlands (Sturm, 1988), in Switzerland (Parret et al., 1993), in Denmark (Røder et al., 1993), in France (Roger et al., 2000). This retrospective approach of clinical cases has also been utilised recently for a multicentre study of cohorts of patients with pneumonia (Meehan et al., 1997).

An evaluation of an infectious diseases service with a control group of patients for whom no consultation was requested has been conducted in Belgium (Byl et al., 1999) and in Switzerland (Fluckiger et al., 2000).

3.2.2. Audits with intervention (before and after) without a control group

A popular method since 1990 is the before and after intervention audit. These are mainly incidence studies which measure the effect of an intervention

Audits for Monitoring the Quality of Antimicrobial Prescriptions 211 aimed at improving prescribing practices. The first studies in the United States

were aimed at controlling costs and numerous studies have been conducted by pharmacists for this purpose (Quintiliani et al., 1987; Seligman, 1981). In gen- eral, there is a global “before and after” analysis, the data of the initial audit are compared to the data of an identical study during (Al-Eidan et al., 2000; Durbin et al., 1981; Lemmen et al., 2001; Raymond et al., 2001) or after inter- vention (Bamberger and Dahl, 1992; Bradley et al., 1999; Drori-Zeides et al., 2000; Frank et al., 1997; Gyssens et al., 1996a, b; White et al., 1997). The analysis can also be conducted over several well-determined periods (Everitt et al., 1990). In this type of analysis, the data of a number of periods of several weeks are gathered and checked. Everitt et al. have compared the choice of surgical prophylaxis during 34 periods of time before intervention and 20 peri- ods after intervention. An intervention study by introducing a protocol for the administration of antibiotics at all caesarean sections found a compliance rate of over 97% with a reduction of the infection rate to around 3% (Taylor, 2000).

3.2.3. Audits with intervention (before and after or simultaneous) with a nonrandomised control group

According to the Cochrane Effective Practice and Organisation of Care (EPOC) group, www.epoc.uottawa.ca, invention studies are considered to have a rigorous design only if they have a parallel control group (simultaneous). This study design has to correct for the error introduced by the choice of a historical control, that is, for the possibility that a spontaneous trend, but not the interven- tion, was responsible for the behavioural change of the prescriber. The control group could be a ward where the intervention has not been implemented (Bartlett et al., 1991; Gyssens et al., 1997). A series of controlled studies has been con- ducted to demonstrate the effect of consultations by infectious diseases physicians on the quality of treatment. The comparison has been made with a group of patients without consultation (sequential analysis) (Gómez et al., 1996) or with a patient group for whom the recommendations by infectious diseases physicians were not followed (Fowler et al., 1998). Some of the controlled studies are retro- spective and have a case control design (Classen et al., 1992; Eron et al., 2001).

3.2.4. Randomised controlled clinical trials

Certain authors have conducted randomised controlled clinical trials in order to compare the effects of their interventions on the quality of prescribing (Ehrenkranz et al., 1992; Fraser et al., 1997). In certain cases, the evaluation of the evaluation process itself was sometimes completely replaced by the evalu- ation of patient outcome (Burton et al., 1991; Destache et al., 1990; Fraser et al., 1997; Singh et al., 2000).

212 Inge C. Gyssens