LINKING PROCESS OF CARE TO OUTCOMES IN QI
3. LINKING PROCESS OF CARE TO OUTCOMES IN QI
“Process of care” is the collective term given to all the activities that con- tribute to healthcare (Crombie and Davies, 1998). For a QI intervention to improve outcomes, it must first impact on process. But which aspects of process are important in CAP? The process of managing any acute medical condition can be described in the form of a pathway or patient journey. Each journey can be broken down into a series of critical control points or “cross- roads,” at which important healthcare decisions (i.e., process of care) are made (Figure 1). Critical control points for CAP can be determined using hazard analysis methodology (Bryan, 1981; Macdonald and Engel, 1996). QI pro- grammes should target processes that are either known to or that are likely to impact on outcomes. Identified critical control points should therefore be “tested” using relevant criteria of causality: (1) strength of association, (2) con- sistency with other studies and evidence, (3) biological or economic credibility, (4) temporal association, and (5) biological or economic gradient (Hill, 1965).
For example, the antibiotic prescription is an important component in the management of CAP. Although there are many potential hazards in antibiotic prescribing (e.g., anaphylaxis), two important hazards that are likely to impact on outcomes for most patients, and that are potentially remediable by an educa- tional intervention, are: (1) delay in administration and (2) inappropriate ther- apy. A number of studies have shown a statistical association between the timely administration of appropriate antibiotics and lower mortality and length of hos- pital stay in CAP (Battleman et al., 2002; Meehan et al., 1997). Both of these aspects of process (i.e., delivery and appropriateness) have biological credibil- ity in that they are consistent with the current understanding of the pathogene- sis of CAP. There is a temporal association in that the process must occur first to impact on outcomes. Finally, there is a biological gradient in that the longer
Table 3. Outcome and process of care measures for clinical CAP research or QI Measure
Comments
Patient-based outcome measures CAP-Sym (Lamping et al., 2002)
CAP-Sym is the only validated CAP-specific patient-based outcome measure. It is validated for use in outpatients only and could be used in audit and research
Clinically based outcome measures Time to clinical stability: One or more of temperature
Not validated as an outcome measure, but the only evidence-based definition of ⬎ 37.8⬚C, pulse ⬎ 100/min, RR ⬎ 24/min, sBP
clinical stability in CAP. Potentially, it could be used as an outcome measure ⬍ 90 mmHg, SaO 2 ⬍ 90%, lack of availability of the oral in CAP research route and abnormal mental status ⫽ clinical instability (Halm et al., 2002)
30-day post-admission mortality (Mortenson et al., 2002) Not validated as an outcome measure, but clearly of importance to all and the evidence-based time point for evaluating mortality in CAP
Processes of care relating to clinical effectiveness Door to antibiotic time (Battleman et al., 2002;
An evidence-based process of care measure for use in QI programmes or research Meehan et al., 1997)
% of patients receiving appropriate antibiotic therapy An evidence-based process of care measure for use in QI programmes or research
Gavin Bar
according to a recognised guideline (Battleman et al., 2002; Gordon et al., 1996; Menendez et al., 2002)
% of hospitalised patients receiving an antibiotic An evidence-based process of care measure for use in QI programmes or research regimen with “atypical” activity (Stahl et al., 1999;
lo w
Waterer et al., 2001)
Pneumonia Guidelines in Pr
% of patients with ICU admission criteria (and without An evidence-based process measure for admission to ICU. However, the sensitivity, a DNR order) admitted to ICU: Two of three minor
specificity etc. are suboptimal. On this basis, it would not be adequate for
population screening, but it could be used as a physician aid in combination FiO 2 ratio ⬍ 250) or one of two major criteria
criteria (sBP ⱕ 90 mmHg, multi-lobar disease, PaO 2 /
with clinical judgement. It should not be used as an outcome measure (need for mechanical ventilation or septic shock) predicted the need for ITU admission (Ewig et al., 1998)
Processes of care relating to economic costs % of low-risk patients (PSI 1–3) managed as outpatients
Not all low-risk patients can be managed as outpatients. The proportion is likely (Atlas et al., 1998; Fine et al., 1997; Marrie et al., 2002)
to depend on local factors, such as the availability of social support and outpatient services
% of patients switched from IV to oral therapy within An evidence-based process of care measure for use in QI programmes or research
actice
24-hr of clinical stability (Halm et al., 2002; Paladino et al., 2002; Rhew et al., 2001)
% of patients discharged within 24-hr of reaching Discharge is also dependent on local factors as outlined above clinical stability (Halm et al., 2002; Rhew et al., 2001)
Economic measures Cost-effectiveness
The costs of the intervention (including development), direct healthcare costs and (see: www.epoc.uottawa.ca/checklist2002.doc)
indirect costs should be quantified and linked with provider and patient outcomes Other measures
Adverse events Not validated as an outcome measure, but of importance to patients, physicians, policy-makers, and drug regulators
Notes: ICU ⫽ intensive care unit; DNR ⫽ do not resuscitate; PSI ⫽ Pneumonia Severity Index; IV ⫽ intravenous.
46 Gavin Barlow
Patient Presents to Primary or Secondary Care
Diagnosis of CAP
Severity Assessment
(Based on the BTS guideline)
Low Risk
Intermediate Risk
High Risk
Clinical Judgement
Administration of Pre-Admission Antibiotics & Prompt Transfer to Hospital
Home Therapy Initial Hospital Assessment & Management
(Social circumstances (Confirmation of diagnosis, reassessment of severity, early delivery of permitting)
antibiotics and, when required, respiratory and cardiac support)
Antibiotics for
Antibiotics for
Low-Risk Patients
High-Risk Patients
(BTS guideline)
(BTS guideline)
Recovery Post-Admission Follow-Up & Management
(Including early referral to high dependency or intensive care units)
Death
Recovery #
Follow-Up & IV to Oral Switch & Outpatient Discharge
Length of Stay
Discharge Planning
Patient-Centred Outcomes*
Figure 1. Based on the Tayside Community-Acquired Pneumonia Project (TAYCAPP), the pathway shows important critical control points and outcomes for CAP. Critical control points are shown in bold boxes. Processes of care measures are shown in shaded boxes. Outcomes are shown in patterned boxes. # Time to clinical stability. *Patient-centred out- comes should be measured at a fixed-point post-admission (e.g., at 30 days).
Pneumonia Guidelines in Practice
47 the time to administer antibiotics (Battleman et al., 2002; Meehan et al., 1997)
and the more inappropriate the therapy (e.g., the extent of under-dosing, lack of “atypical” cover [Stahl et al., 1999] or the use of oral therapy in a severely ill patient), the poorer the outcomes are likely to be.
The failure to draw a blood culture prior to antibiotic therapy is also a potential hazard that is potentially remediable by an educational intervention. While this process is undoubtedly of importance, for example, to detect bacter- aemia and rationalise antibiotic therapy, there is little biological credibility to the hypothesis that the act of drawing a blood culture is likely to lead to improved outcomes. Additionally, there is no obvious biological gradient and there is doubt about the impact of microbiological investigations on outcomes (Campbell et al., 2003; Sanyal et al., 1999). The association found in some observational studies (Meehan et al., 1997) is likely to be due to confounding by the overall higher quality of care, including the efficient delivery of appro- priate antibiotics and other therapy, provided by physicians who decide to take
a blood culture prior to administering antibiotics. For a QI intervention to impact on outcomes therefore, it is important to target processes of care that determine outcome.
3.1. What are the advantages of process of care measures in QI?
Achievement of important aspects of process (e.g., door to antibiotic time) can be measured as part of QI initiatives instead of or as well as outcome mea- sures, such as 30-day mortality and quality of life. There are a number of advan- tages in this approach. In contrast to many outcome measures, process of care measures are: easier to measure and interpret; less prone to the effects of case- mix; indicate the aspects of care that need to change; and are more sensitive to the quality of care (Crombie and Davies, 1998; Goddard et al., 2002; Mant and Hicks, 1995). For example, the lack of sensitivity of mortality as an indicator of quality has previously been demonstrated for myocardial infarction (Mant and Hicks, 1995) and is illustrated in CAP by the following example. Waterer et al. recently found single effective therapy (SET) to be less effective than dual effective therapy (DET) in the treatment of severe bacteraemic pneumococcal pneumonia (patients receiving SET had a mortality of 18% vs 7% for those receiv- ing DET). If this data is used in a hypothetical model with the assumption that DET is the “standard of care” and that hospital A is 100% adherent with DET (mortality ⫽ 7%) and hospital B is 50% adherent with DET (mortality ⫽ 13%), and that case-mix and process in hospitals A and B are otherwise identical, to statistically detect (P ⱕ 0.05 with 80% power) the difference in quality of care by using mortality (i.e., 7% vs 13%), both hospitals would need to have data
48 Gavin Barlow from 338 patients with severe bacteraemic pneumococcal pneumonia. In
contrast, to statistically detect the difference in quality of care by measuring the process, that is, adherence with DET (100% vs 50%), both hospitals would require data from only 8 patients (Sample sizes calculated using CLINSTAT, Martin Bland, St. George’s Hospital Medical School, London, UK, 1996).