Title: Effectiveness of the Austrian Disease Management Program for diabetes: a cohort study based on health insurance provider's routine data

Transcription

1 Author's response to reviews Title: Effectiveness of the Austrian Disease Management Program for diabetes: a cohort study based on health insurance provider's routine data Authors: Herwig Ostermann (herwig.ostermann@umit.at) Victoria Hoess (victoria.hoess@umit.at) Micheal Mueller (michael.mueller@svagw.at) Version: 2 Date: 13 March 2012 Author's response to reviews: see over

2 Comments to Reviewer 1 (Renee Stark) First of all, the authors would like to thank the reviewer for her valuable comments. In fact, we have tried to incorporate the reviewer s suggestions whenever possible. Study population 1. The authors do not clarify which type of diabetes they are studying. I assume that the authors are intending to assess patients with type 2 diabetes (which is also the only type of diabetes included in the DMP program in Styria according to internet information) but the authors do not define this population in their paper this must be clarified in all parts of the paper. The authors clarified that only type 2 diabetics were studied. In addition to changes throughout the text, the authors changed the title of the manuscript, too. Study population: 2. Furthermore, if the authors are only studying type 2 diabetics, although the diagnosis is mostly certain in the DMP population (because the physicians have included the patients in the DMP program), this is not true for the controls and the authors do not describe any steps taken to exclude patients with Type 1 diabetes out of the control group. Having Type 1 diabetics in the control group leads to biased results since this group of patients will likely have had the diabetes for a longer period of time, may require closer monitoring for their blood glucose control and insulin and maybe more likely to have complications and complications requiring hospitalisation. If distinction between Type 1 and Type 2 diabetics is not possible according to the data (are some diagnoses available from the hospital admission and discharge data?), the authors should consider performing separate analyses according to medication intake comparing only patients taking oral antidiabetics or oral anti-diabetics with insulin or by excluding patients younger than 40 years of age and only taking insulin from the controls. Another strategy could be to adjust all analyses for the types of medication taken for treatment of diabetes and then discuss differences between the groups also regarding the possibility that type 1 diabetics could be included in the controls. If type 1 diabetics are left in the control group the authors should discuss what proportion of controls are likely to be type 1 and should also discuss their effects on the calculated costs. As the authors did not have access to inpatient diagnosis data, the authors adopted the reviewer s suggestion and performed separate analyses according to medication intake. Analyses: 1. The authors should support the use of the t-test to analyse utilisation and cost data. Are cost data and utilisation data normally distributed in their sample? It could be expected that both would have a skewed distribution. If regression analyses are considered by the authors, they should consider if using a gamma distribution would be appropriate in their cost analyses. The authors reconsidered the data analysis performed due to the reviewers comments and included tests for normal distribution for metric variables. As the reviewer expected most variables turned out to have a skewed distribution. As the metric variables assessed and in particular cost as well as overall utilisation data did not show an extremely skewed distribution, the authors considered that the application of non-parametric tests (Mann-Whitney U-Test) as being an appropriate procedure.

3 Analyses: 2. Furthermore, since the study is not randomised, one should adjust at least for age and sex especially if there are differences in age between the groups using simple testing. The authors did adjust for sex and age as suggested by the reviewer and indicated the adjustment in the section in data analysis. Results: 1. Could some differences between the groups regarding testing for HbA1c and lipid levels be due to the fact that levels were tested in the hospital? According to hospitalization rates of the revised study population, the share of patients hospitalized in 2009 was almost equal (35% of DMP patients vs. 35.6% of non-participating patients). Even though some differences in the average number of stays of hospitalized patients persist (1.8 stays for DMP patients vs. 2.2 stays for nonparticipating patients), these differences are unlikely to contribute to the observed differences in HbA1c and lipid level testing to a major extent. Results: 2. The authors should also discuss whether the diabetes of patients in the control group could be cared for in out-patient clinics in the hospital (0 hospital days as discussed in reference 22 of the paper) and whether this would be evident in their data set. The authors should also discuss what the effect of receiving treatment or primary care for diabetes in hospitals would have on the costs (increase or decrease costs). When analyzing hospitalization rates, the authors only included inpatient stays due to the fact, that data on stays in outpatient clinics in the hospital are only systematically reported to the insurer in case of 0-day stays but not in the case of regular services provided in hospitals outpatient clinics. The latter services are predominantly remunerated as lump-sum payments out of the centrally pooled hospital payment funds; therefore reporting of these cases to the insurance institution is not required due to financial reasons. Overall, cost data on different outpatient services provided in Austrian hospital clinics is very rare and only exists for some selected procedures such as MRT or mammography screenings. However, even for this procedures, evidence is not uniform in terms of its direction, resulting in cost advantages for services provided by specialists in one federal state to cost advantages for outpatient clinics in another state (for further evidence see: Rechnungshof (2011): Finanzierung und Kosten von Leistungen in Spitalsambulanzen und Ordinationen. Wien). Due to this lacking data for the Austrian context, the authors decided not to discuss potential cost effects of shifting health service delivery from medical specialists to outpatient clinics in hospitals. However, more information was provided on the exclusion of 0-day stays when presenting the outcome measures for hospitalization rates in the methods section of the manuscript. Minor revisions: Under Methods and Population, line 4: please clarify what insured by an author social insurance institution means. The authors changed this passage into: insured by another social insurance institution

4 Comments to Reviewer 2 (Soeren Mattke) First of all, the authors would like to thank the reviewer for his critical comments. In fact, the authors have tried to expand the design of the study and included data on costs and utilization before the start of the DMP in order to meet the reviewer s critique. Thank you for the opportunity to review your manuscript. Before I go into details, pls allow me to verify that my understanding of your approach is correct. You use data for the first year of the DMP and compare utilization and cost for diabetics who are enrolled to those who are not. If that is correct, your design that not allow drawing valid conclusions. While you state that the overall population is quite homogenous, it is still entirely possible that the enrollees are systematically different from the non-enrollees and that those underlying differences, rather than the DMP, account for the differences in cost and utilization. In fact, you do find differences in age. But without data on cost/utilization before program start, clinical severity and comorbidities, your results are impossible to interpret. If I misunderstood, pls clarify your approach and I'm happy to review again. In the original design, the authors used 2009 data in order to compare costs as well as out- und inpatient services utilization of type 2 diabetics enrolled in the Austrian disease management program to those patients receiving regular treatment. As the DMP started in 2007, participating patients were on average enrolled 1 year prior to the study period ( ). However the authors agree with the reviewer s comment that the two populations compared may be different in terms of specific characteristics, which might also cause overall differences in costs as well as utilization. Hence, the authors have somewhat changed the study design for the revised manuscript: First, the authors did control for sex and age in the control group. Second, the authors also integrated data on utilization and costs for both study groups for 2006 providing overall information on cost/utilization before the program started as shown in the revised table 6. Even though the authors did not gain access to the full set of the insurers patients records for 2006, which would have been necessary in order to provide 2006 data for tables 2-5, table 6 now provides useful information on the baseline characteristics on costs as well as utilization for both study groups, indicating different patterns of costs of outpatient care for both study groups before the start of the DMP, but also different developments in terms of the numbers of outpatient services received as well as average days spent in hospital in particular. Concerning the reviewer s suggestion on integrating clinical severity of the disease as well as comorbidities at baseline, the authors were not able to gain any information on these parameters as clinical reports including data on diagnoses are held by hospitals and integrating these data with insurer s records what raise severe data protection concerns. As far as diagnoses data for outpatient care is concerned it has to be noted that Austrian GPs and specialists are not obliged to report data on diagnoses to insurers.

5 Comments to Reviewer 3 (Ulrike Rothe) First of all, the authors would like to thank the reviewer for her valuable comments. In fact, we have tried to incorporate the reviewer s suggestions whenever possible. 1) Nevertheless the focus of better quality of care in the evaluation study is limited to the process quality. Therefore, please add in the chapter Outcome measures in the first sentence the word process prior the word quality. You could not observe the outcome quality because of the health insurance database, could you? Furthermore the Austrian DMP reached only about 2,5% of all medication treated diabetic patients in the region. This is contradictory to the statement: As for other the Austrian diabetes DMP incorporates a population-based strategy.. Why is the participation rate not higher, although there are quite high incentives for physicians (a lump sum payment of 100 p.a. and an extra reimbursement of 55)? Can you identify reasons for that? The authors added the word process as the reviewer suggested. Moreover the authors discussed low participation rates of the Austrian diabetes DMP in the discussion section focusing on currently dysfunctional financial incentives for insurers. 2) Another question: Are the GP s and the specialists working together (integrated care)? Currently, participating physicians, that are most commonly either GPs or specialists for internal medicine, receive a lump sum payment, which also includes compensation for the coordination of care amongst other specialists as well as outpatient clinics and inpatient care. However, models of integrated care in terms of established cooperation amongst different providers of outpatient and inpatient care along with an adequate financing scheme have not been developed yet. The authors have included a corresponding passage in the article when presenting the Austrian diabetes DMP. 3) What s about the metabolic syndrome? You wrote only: achievement of optimal blood sugar management., there are no results concerning the blood pressure, are there? In fact, the Austrian diabetes does not explicitly mention the metabolic syndrome. Due to the fact, that we only gained permission to the insurer s records on outpatient care consisting of services provided as well as its corresponding fees, we did not have an information on blood pressure or any other parameter indicating outcome quality. 4) Please, avoid redundance in the tables. Therefore, please, rename the table 3 into table 2a (with significant results) and table 2 into table 2b and remove all redundant results (in table 2b now only the non-significant results). We integrated tables 2 and 3 into one new table (table 2).

6 5) I miss some very important references to show the possibility of improvement of outcome quality of care by diabetes disease management statewide, for example, published in Diabetes Care 2008; 31 (5): Please, add this reference, for example, in the section discussion page 10, line 7. Thank you very much for this very interesting and also relevant source. In fact, we added this paper to our reference list and also cited the authors in the discussion section. 6) Last, you should conclude according to the new reference whether to adopt disease management as a standard benefit or not this depends on the kind of the disease management program! The better way is the chronic care model by Wagner et al. for multi-morbid patients in an integrated care setting. The last sentence should conclude with: the effects of the Austrian diabetes DMP and with intermediate outcomes. Thank you also for this comments, which have been included in the revised conclusion section.