Abstract
Purpose:
Computerized decision support systems (CDSSs) are often part of a multifaceted intervention to improve diabetes care. We reviewed the effects of CDSSs alone or in combination with other supportive tools in primary care for type 2 diabetes mellitus (T2DM).
Materials and Methods:
A systematic literature search was conducted for January 1990–July 2011 in PubMed, Embase, and the Cochrane Database and by consulting reference lists. Randomized controlled trials (RCTs) in general practice were selected if the interventions consisted of a CDSS alone or combined with a reminder system and/or feedback on performance and/or case management. The intervention had to be compared with usual care. Two pairs of reviewers independently abstracted all available data. The data were categorized by process of care and patient outcome measures.
Results:
Twenty RCTs met inclusion criteria. In 14 studies a CDSS was combined with another intervention. Two studies were left out of the analysis because of low quality. Four studies with a CDSS alone and four studies with a CDSS and reminders showed improvements of the process of care. CDSS with feedback on performance with or without reminders improved the process of care (one study) and patient outcome (two studies). CDSS with case management improved patient outcome (two studies). CDSS with reminders, feedback on performance, and case management improved both patient outcome and the process of care (two studies).
Conclusions:
CDSSs used by healthcare providers in primary T2DM care are effective in improving the process of care; adding feedback on performance and/or case management may also improve patient outcome.
Introduction
Unfortunately, there is no international definition of CDSS, but in most diabetes management systems physicians, practice nurses, or patients manually enter patient characteristics into the CDSS, or the electronic medical record is electronically searched for patient characteristics. These individual patient characteristics are then used in software algorithms and/or matched to a computerized knowledge base, to generate treatment recommendations.
Garg et al. 7 performed a review on CDSS in clinical care, showing mainly improvements in the practitioner's performance. Another review, evaluating the effects of interactive computer-assisted technology in T2DM care, concluded that there is growing evidence that information technology improves diabetes care. 8 However, this study evaluated both randomized controlled trials (RCTs) and observational studies with a broad range of interventions, such as education, disease management, telephone automated calls, and telemedicine; it aimed at both healthcare provider and patient and included both primary and secondary care. Because of this heterogeneity general inferences were impaired.
We aimed to study whether a CDSS alone or a CDSS in combination with a reminder system or with feedback on performance or as part of a case management system improves both patients' outcome and practitioners' performance.
Materials and Methods
Eligibility criteria
Eligible studies were randomized clinical trials published in peer-reviewed journals in English that compared the effectiveness of T2DM care with a CDSS against that of T2DM care without a CDSS on clinical performance (measure of process of care) and/or patient outcome. We searched for management interventions developed for use by a diabetes care provider in general practice/primary care. The CDSS should contain a computer system that used patient characteristics to generate decision support by a software algorithm based on a diabetes guideline. The CDSS could also function as a recall system and/or make it possible to give feedback on performance on patient level and/or healthcare professional level and/or be integrated in a so-called case management system.
Computerized glucose monitoring systems, diabetes self-management programs, digital eye screening programs, or patient education systems were excluded. The studies should include only T2DM patients and have a follow-up of at least 6 months.
Search strategy
Published studies were identified by searching the electronic databases of PubMed, Embase, and the Cochrane Library. A universal definition of a CDSS is not available. However, based on our above-mentioned operational definition of a CDSS, the following search terms were used: “diabetes” AND (“decision support” OR “computer-assisted decision making” OR “computer” OR “artificial intelligence” OR “electronic intervention” OR “Internet” OR “reminder systems” OR “recall system” OR “feedback” OR “benchmark”) AND (“randomised” OR “randomized” OR “RCT” OR “trial” OR “evaluation studies”). Because a more widespread use of CDSS started about two decades ago, we included articles published between January 1990 and July 2011. Finally, manual searches were performed by screening the reference sections of the relevant review articles and of the selected RCTs.
Study selection
Titles and abstracts were independently reviewed by two pairs of investigators for eligibility. The first 200 titles were reviewed by all investigators. The results were compared and discussed in order to reduce the variation in interpretation of inclusion and exclusion criteria between the reviewers. Full text articles were retrieved if any reviewer considered a citation potentially relevant. Two investigators then independently judged the full text of potentially eligible articles. Disagreements were resolved by discussion. If no consensus could be achieved, a third investigator was asked. When comparable outcome data of a study were published twice, we cited the publication providing most data and with the longest follow-up.
Data extraction
Two reviewers independently extracted the following data from all included studies: study setting, study methods, study intervention characteristics, and study outcomes. Study outcome was categorized by process of care measures and by patient outcomes. Process of care measures are, for example, the frequency of glycosylated hemoglobin (HbA1c) testing or starting medication when treatment goals are not met. Patient outcomes measures are, for example, the actual change in HbA1c, cholesterol level, or blood pressure. The same pairs of investigators worked together, as in study selection. Disagreements were resolved by consensus, and where no consensus could be achieved, a third investigator decided.
Methodological validity
All studies were scored for methodological validity on a 2-point scale: yes (1 point) or no or unclear (0 points). The nine methodological validity indicators from the Dutch Cochrane Center were used: (1) intervention randomized; (2) randomization order not known by person who included patients/practices; (3) patients blinded; (4) therapist blinded; (5) outcome assessor blinded; (6) groups comparable; (7) proportion of follow-up of all included patients high enough; (8) included patients analyzed in group of inclusion; and (9) groups equally treated, except for the intervention. 9 Studies could be cluster randomized or patient randomized. Whenever studies were cluster randomized, we identified whether appropriate analysis methods (e.g., generalized estimated equations) were used in order to correct for clustering. Only studies that randomized patients or studies that were cluster randomized and applied appropriate methods to take cluster effects into account scored 1 point for the first item of the Cochrane Center list. A 10th indicator was added: the use of power calculations. Adding all validity indicators the studies could score a maximum of 10 points. Only the results of studies that scored 5 or more points were used. Furthermore, we reported country, commercial funding of studies, and the number of patients.
We presented studies as a group, depending on the type of intervention or combination of interventions.
Statistical analysis
First, we assessed the eligibility of the study. Reviewer agreement on study eligibility was quantified using the Cohen κ value.
We divided the eligible studies into six categories, based on the intervention used: (1) a CDSS alone; (2) a CDSS combined with a reminder system; (3) a CDSS with feedback on performance; (4) a CDSS with case management or with case management and reminders; (5) a CDSS with a reminder system and feedback on performance; or (6) a CDSS with a reminder system, feedback on performance, and case management. The 10 validity indicators were used to express study methodological validity. We calculated means, the SD, and the range. Finally, the effectiveness of the interventions was compared by describing the measures as mentioned in the articles. We distinguished “process measures” and “patient outcomes.”
Results
Selection of studies
The electronic database search revealed 2,290 citations, when duplicate citations between databases were removed. The titles of these citations were reviewed and revealed 548 abstracts. After abstract selection 121 articles remained for full text review. Eventually, 26 articles met our inclusion criteria. There were two duplicate publications: Glasgow et al. 10,11 with 6 months of follow-up 10 and 12 months of follow-up 11 and Lobach et al. 12,13 with baseline compliance levels 12 and 6 months of follow-up. 13 The study from Phillips et al. 14 and Ziemer et al. 6 regarded the same study population, with different outcome measures. This also applies to the three studies of Cleveringa et al. 15 –17 and to the studies from Khan et al. 18 and MacLean et al. 19 Therefore eventually 20 RCTs were included. Ninety-five articles were excluded because of different reasons, for example, review article (n=14), no RCT (n=22), no CDSS used in the intervention (n=26), glucose monitoring system (n=10), or diabetes self-management program (n=11) (Fig. 1).

Summary of the literature search. CDSS, computerized decision support system; RCT, randomized controlled trial.
There was substantial agreement between the reviewers for article inclusion, with a change-corrected agreement between two pairs of independent investigators of κ=0.75 versus κ=0.76.
Methodological validity assessment (Table 1)
In eight trials patients were randomized 20 –26 ; one of them also corrected for clustering. 25 The other 12 trials had a cluster randomized design, 6,11,13 –17,19,27 –34 and 10 trials adjusted for clustering in the analysis. 6,11,14,16,30 –35 Twelve trials reported a power calculation for a specified difference between groups and a specific outcome. 6,11,14,20,22,26,29,31 –34,36
Cleveringa et al., 15 –17 Phillips et al. 14 and Ziemer et al., 6 and MacLean et al. 19 and Khan et al. 18 represent the same respective study with different outcome parameters.
Value in randomized column is 1 if patients were randomized or when cluster randomization with the generalized estimating equation (GEE) was used.
Total validity score is the sum of randomized, blinded (randomization order, patient, physician, and outcome assessor), groups comparable, follow-up of <70%, patients analyzed in group inclusion, groups equally treated, and power calculation columns.
Not meeting minimal validity score.
NA, not applicable.
Positive scores on the methodological validity indicators blinding of patient, therapist, and outcome assessor were poor: 17%, 4%, and 33%, respectively. On the methodological validity scale the mean score was 6.4 (SD, 1.3) with a range from 3 to 8. Two studies scored less than 5 points 13,29 and were excluded from the analysis (Table 1).
Categories of studies
The 20 included studies were published between 1993 and 2011. The number of trials increased with time: one in 1990–1994, one in 1995–1999, five in 2000–2004, eight in 2005–2009, and five in 2009–2011. Fourteen studies were conducted in the United States, one in Canada, one in the United Kingdom, one in Norway, one in Denmark, one in Korea, and one in The Netherlands. The number of patients included varied between 62 20 and 7,412. 19 Sixteen of the studies described funding from the public sector, and four obtained funding from the private sector. In six studies the only intervention was a CDSS (Table 2); the other studies regarded a multifaceted intervention in which the CDSS was combined with a reminder system (Table 3), CDSS with feedback on performance (Table 4), CDSS with case management or CDSS with case management and reminders (Table 5), CDSS with a reminder system and feedback on performance (Table 6), and CDSS with a reminder system, feedback on performance, and case management (Table 7).
DBP, diastolic blood pressure; DM, diabetes mellitus; EMR, electronic medical record; HbA1c, glycosylated hemoglobin; HDL, high-density lipoprotein; LDL, low-density lipoprotein; NS, not significant; SBP, systolic blood pressure.
Same study population, same intervention, different outcome. The study compared four interventions. Here the results of the computerized decision support system with reminders are compared with usual care.
ACE, angiotensin converting enzyme; BMI, body mass index; EMR, electronic medical record; HbA1c, glycosylated hemoglobin; IPCAAD, Improving Primary Care of African Americans with Diabetes; LDL, low-density lipoprotein; NS, not significant; OR, odds ratio; SBP, systolic blood pressure; VDIS, Vermont Diabetes Information System.
Same study population, same intervention, different outcome. The study compared four interventions. Here the results of CDSS with feedback on performance is compared with usual care.
Not all the study outcomes are listed here.
CI, confidence interval; GP, general practitioner; HbA1c, glycosylated hemoglobin; HDL, high-density lipoprotein; IPCAAD, Improving Primary Care of African Americans with Diabetes; LDL, low-density lipoprotein; NS, not significant; SBP, systolic blood pressure; T2DM, type 2 diabetes mellitus.
DBP, diastolic blood pressure; GP, general practitioner; HbA1c, glycosylated hemoglobin; HDL, high-density lipoprotein; NS, not significant; SBP, systolic blood pressure.
Same study population, same intervention, different outcome. The study compared four interventions. Here the results of the computerized decision support system with reminders and feedback on performance is compared with usual care.
DBP, diastolic blood pressure; GP, general practitioner; HbA1c, glycosylated hemoglobin; LDL, low-density lipoprotein; IPCAAD, Improving Primary Care of African Americans with Diabetes; NS, not significant; SBP, systolic blood pressure.
Same study population, same intervention, different outcome.
10-year United Kingdom Prospective Diabetes Study (UKPDS) coronary heart disease (CHD) risk is the estimated risk on death from CHD calculated by using the UKPDS risk engine.
CI, confidence interval; DBP, diastolic blood pressure; DCP, diabetes care protocol; DHP, Diabetes Health Profile; HbA1c, glycosylated hemoglobin; LDL, low-density lipoprotein; NS, not significant; QALY, quality-adjusted life-years; SBP, systolic blood pressure; SF-36, Short Form 36.
Because Phillips et al. 14 and Ziemer et al. 6 compared both usual care, CDSS with reminders, CDSS with feedback on performance, and CDSS with feedback on performance and reminders, these studies appear in three tables. In all these different studies one intervention group is compared with the usual-care control group.
Effectiveness of a CDSS alone (Table 2)
The four studies either used a CDSS or a Web-based diabetes management support system. They were performed between 2004 and 2008.
The studies show improvements in the process of care, like the number of completed foot exams, 32 an increase in the mean sum of measures, 31 the number of completed laboratory tests, and completed patient-centered activities. 11 The most recent study showed more medication adjustments by the general practitioner because patients took more initiative to improve their blood values. 27 Improvements in patient outcome were not significant. However, in one study the systolic blood pressure increased significantly more in the intervention group. 32
Effectiveness of a CDSS with reminders (Table 3)
Five studies, reported in seven articles between 2002 and 2010, used a CDSS with reminders. Three studies only showed improvements in the process of care. Improvements were found in yearly HbA1c testing, retinal exams, and the composite of three tests, as well as in laboratory monitoring, 18 low-density lipoprotein testing, and the composite of all process measures. 34 One study showed that significantly more treatment adjustments were made when glucose levels exceeded 8.3 mmol/L, 6,14 and one study showed that the intervention was associated with reduced hospital and emergency department utilization and expenses. 19 Two other two studies showed little improvement in patient outcome: blood pressure and HbA1c 36 and in fewer patients having HbA1c >9.5%. 25
Effectiveness of a CDSS and feedback on performance (Table 4)
In three studies (four publications), a CDSS with feedback on performance was compared with usual care. In one study the HbA1c level improved significantly, 23 but not in another study. 14 The process of care improved by better prescription patterns and a better stimulation to follow the guidelines more closely in one study 28 and intensification of therapy in another study. 6 In the latter a multivariable analysis showed that feedback on performance independently facilitated attainment of American Diabetes Association goals for HbA1c (<7%) and systolic blood pressure (<130 mm Hg) and also independently contributed to therapy intensification and consequently to a fall in HbA1c level. 6
Effectiveness of a CDSS with case management or with case management and reminders (Table 5)
In both studies that assessed this type of intervention, performed in 2007 and 2009, respectively, patient outcome improved. The first study with only 62 patients led to significant improvements in HbA1c level, total cholesterol, high-density lipoprotein-cholesterol, weight, and systolic blood pressure. 20 In the second study both HbA1c level and the percentage of patients reaching HbA1c <7% improved significantly, but no differences were found in general practitioner visits, specialist visits, or inpatient days. 26
Effectiveness of a CDSS with reminders and feedback on performance (Table 6)
In four studies (five publications), performed between 1993 and 2011, a CDSS was combined with reminders and feedback on performance. In three of them the patient outcome HbA1c level was improved. 14,22,30 The process of care improved by treatment intensification in one of the three studies mentioned before. 6 The oldest study did not show improvements in the patient outcome HbA1c level; however, the process of care did by a significant decrease in both the percentage of patients who had no doctor's review and the percentage of patients without HbA1c testing. 24
Effectiveness of a CDSS with reminders, feedback on performance, and case management (Table 7)
In two more recent large cluster randomized trials all four interventions were combined. In both studies patient outcome improved either by an improved composite end point of HbA1c level, systolic blood pressure, and low-density lipoprotein-cholesterol 33 or by an improved 10-year United Kingdom Prospective Diabetes Study coronary heart disease risk estimate. 16 The process of care also significantly improved in one study. 33 For one intervention it was shown that it was not cost-effective 15 and that there was no negative influence on health status. 17
Discussion
We evaluated RCTs that studied the effectiveness of a CDSS alone or in combination with other supportive tools to improve the quality of primary T2DM care. We distinguished “process measures” and “patient outcome.” A CDSS alone seems ineffective in improving patient outcome.
Comparison with other studies
Our findings are in accordance with earlier reviews that concluded that information technology alone, like a CDSS, mainly improves the process of diabetes care. 7,8
Our finding that a CDSS with reminders improves the process of care, but not the patient outcome, is supported by an earlier review. Reminders facilitate a structured and regular review of patients; they improve the process of care. 4
Our conclusion with regard to the effectiveness of a CDSS combined with feedback on performance is ambiguous. This seems to be in line with earlier findings. A Cochrane review regarding audit and feedback reported positive effects on the process of care but not on patient outcome 37 ; however, this review was hampered by inadequate reporting of study methods for almost all studies. Looking at the results of the Improving Primary Care of African Americans with Diabetes Study, 6 we might conclude more optimistically that the combination of CDSS and feedback on performance is probably an important tool to improve patient outcome in diabetes care.
The combination of a CDSS with feedback on performance, reminders, and case management seems to be the most effective. This finding is supported by evidence on the Chronic Care Model, 38 in which making care delivery more team-based and planned and making better use of registry-based information belong to the key determinants of improved patient outcomes. 4
Adding patient education and nurses that function as case-manager also improves patient outcome. 4,39 This review also concludes that case-managers can improve patient outcome. The effects of electronic patient education systems were, however, excluded in this review.
Strengths and limitations
This is the first review on the effectiveness of a CDSS that focused on primary care T2DM management programs. Because most CDSSs are part of a broader intervention, we distinguished six different combinations of interventions. Doing so, we could find the interventions in which a CDSS is most likely to improve both process and outcome of diabetes care.
The methodological quality of the studies was assessed. It appeared that the scores for blinding of patients, therapists, and outcome assessors were low, which may be caused by the complexity of these interventions. By excluding two studies the results of our review are more robust.
The funding of the studies was recorded. Four trials were privately funded; however, the authors of these studies did not disclose business relationship or financial gain from the technology they were studying. Most studies were publicly funded. Because of this we think we might conclude that conflict of interest is not a very important issue in this research domain.
Our study has also limitations. First, we studied interventions from a two-decade period. The technology of early CDSS is quite different from the more recent ones, and therefore the overall conclusions will be influenced by the effects of CDSSs that are no longer existing or whose technology may now be obsolete. Second, we included only published articles, all with some significant results. Because studies not showing a statistically significant superior effect of a CDSS may be less easily accepted for publication, a publication bias cannot be ruled out. Third, because of the heterogeneity of the interventions and outcome measures, a meta-analysis was not possible. Finally, because the follow-up period of most studies was only 1 year, it was not possible to assess the long-term outcome of a CDSS with or without additional support.
Our search strategy revealed only one cost-effectiveness study regarding a CDSS-based primary diabetes care management system. This hampers conclusions on the economic aspects of CDSSs.
Conclusions
CDSSs in primary T2DM care are effective in improving the process of care. The combination of a CDSS with feedback on performance, reminders, and case management is likely to be the most effective in improving patient outcome.
The long-term effectiveness and the cost-effectiveness of a CDSS in a primary care–based multifaceted diabetes management program remain to be elucidated.
Footnotes
Acknowledgments
This study was made possible by an unrestricted grant from Pfizer B.V.
Author Disclosure Statement
No competing financial interests exist. F.G.W.C. had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
