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Treatment gaps for hypertension management in rural Canadian patients with type 2 diabetes mellitus
CLINICAL THERAPEUTICS® / VOL. 26, NO. 4, 2004
Brief Report
Treatment Gaps for Hypertension Management in Rural Canadian Patients with Type 2 Diabetes Mellitus Alison L. Supina, BScPharm,1,4 Lisa M. Guirguis, BScPharm, MSc,1 Sumit R. Majumdar, MD, MPH, FRCPC,1,2 Richard Z. Lewanczuk, MD, PhD, FRCPC,2 T.K. Lee, MD, FRCPC,2,3 Ellen L. Toth, MD, FRCPC,1,2 and Jeffrey A. Johnson, PhD1,4 1Alliance
for Canadian Health Outcomes Research in Diabetes, Institute of Health Economics, 2Department of Medicine, University of Alberta, 3Department of Medicine, Grey Nuns Hospital, and 4Department of Public Health Sciences, University of Alberta, Edmonton, Alberta, Canada
ABSTRACT
Background: There were a reported 2.2 million Canadians living with diabetes mellitus (DM) in 2002, of whom 1.98 million (90.0%) had type 2 DM. In addition, there are ~60,000 new cases of type 2 DM diagnosed in Canada each year. However, the research shows that evidence and guidelines for management of hypertension in DM are not always translated into clinical practice. In rural areas, factors affecting implementation of recommendations and/or guidelines are less well understood, although some studies suggest that urban practices provide higher quality of care overall than rural areas. Objective: The goal of this study was to describe the patterns of medication use for hypertension for patients with type 2 DM in rural northern Alberta, Canada. We also tried to identify treatment gaps and opportunities for prescribing antihypertensives relative to the Canadian Diabetes Association’s 1998 Clinical Practice Guidelines for the Management of Diabetes in Canada and the Canadian Hypertension Society Recommendations Working Group’s 2003 Canadian Recommendations for the Management of Hypertension: Therapy. Methods: This study was conducted at the Institute of Health Economics and the University of Alberta (Edmonton, Alberta, Canada). We collected information from a cohort of patients aged ≥20 years with type 2 DM living in 2 adjacent rural regions of northern Alberta, Canada, at the time of enrollment in a diabetes care quality-improvement program as part of the Diabetes Outreach Van Enhancement (DOVE) study. Treatment gaps were determined by comparing antihypertensive pharmacotherapy with a blood pressure (BP) target of ≤130/≤85 mm Hg. We used multivariate regression analyses to determine the associations between sociodemographic and clinical characteristics and treatment gaps. Results: A total of 392 patients (229 women, 164 men; mean [SD] age, 62.3 [12.5] years) with type 2 DM were included in this analysis. Patients had a mean (SD) duration of diabetes of 8.3 (8.5) years. A total of 75.8% (297/392) of the study population had hypertension, and most (236/392 [60.2%]) were receiving some pharmacotherapy. Treatment gaps were present; 42.7% (n = 67) of patients not receiving pharmacotherapy for hypertension were above the established BP targets. For patients receiving monotherapy, 70% were not at BP targets. For patients receiving dual, triple, and ≥4 medications, 65%, 66%, and 46%, respectively, were not at BP targets. After controlling for systolic blood pressure, male sex (adjusted odds ratio [aOR], 2.17; 95% CI, 1.17–4.03), This article was presented in poster form at the annual meeting of the Canadian Association of Population Therapeutics; Toronto, Ontario, Canada; April 14–16, 2002, and in poster form at the annual meeting of the Canadian Diabetes Association; Ottawa, Ontario, Canada, October 16–18, 2003. Accepted for publication January 21, 2004. Printed in the USA. Reproduction in whole or part is not permitted. 0149-2918/04/$19.00
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older age (aOR, 1.80 per decade; 95% CI, 1.51–2.09), lower self-reported physical health (aOR, 0.68; 95% CI, 0.41–0.96), higher body mass index (aOR, 1.05; 95% CI, 1.01–1.10), and past/current smoking (aOR, 1.95; 95% CI, 1.01–3.76) were all significantly associated with a lack of treatment for hypertension. Conclusions: Treatment gaps in the management of hypertension exist in these rural Canadian patients with type 2 DM. Cardiovascular risk may be underestimated in these patients, particularly among younger patients and women, and those with multiple non-DM risk factors. These are patient subgroups that should be targeted as opportunities to improve hypertension management at the population level. (Clin Ther. 2004;26:598–606) Copyright © 2004 Excerpta Medica, Inc. Key words: type 2 diabetes, hypertension, guidelines, treatment gaps.
pressure (BP) also reduces the risk for microvascular complications—such as vision impairment and endstage renal disease—by as much as 10%.7 Despite this strong proof, research also shows that evidence and guidelines for management of hypertension in DM are not always translated into clinical practice. Recent studies in urban centers in the United States7–10 suggest that ~60% to 90% of individuals with type 2 DM are not at BP targets. In rural areas, factors affecting the implementation of practice recommendations and/or guidelines are less well understood, although some studies11–13 suggest that urban practices provide a higher quality of care overall than rural areas. The purpose of the current study was to describe the patterns of antihypertensive medication use by patients with type 2 DM in rural, northern Alberta, Canada. We also tried to identify treatment gaps and opportunities for prescribing antihypertensive medication in type 2 DM relative to guidelines for hypertension management.
INTRODUCTION
PATIENTS AND METHODS The Diabetes Outreach Van Enhancement Study
The prevalence of diabetes mellitus (DM) is increasing rapidly.1,2 Health Canada,2 the federal department responsible for helping the people of Canada maintain and improve their health, reported that 2.2 million Canadians were living with DM in 2002, 1.98 million (90.0%) of whom had type 2 DM. In addition, ~60,000 new cases of type 2 DM are diagnosed in Canada each year.2 This rapid increase in prevalence may be a result of enhanced screening and disease awareness; however, responsibility is more likely to lie with an aging population and lifestyle considerations. Cardiovascular disease is the leading cause of death in patients with type 2 DM and is associated with significant morbidity and mortality.3,4 Also, the direct medical costs associated with macrovascular complications are much greater than those associated with microvascular complications.5,6 Studies involving intensive treatment of multiple risk factors to prevent macro- and microvascular complications consistently show that aggressive treatment of hypertension can result in up to 50% decreased risk reductions in cardiovascular morbidity and mortality, more so than control of blood glucose and cholesterol levels.7 Vijan and Hayward7 suggested that aggressive treatment of elevated blood
The Diabetes Outreach Van Enhancement (DOVE) study14,15 was a prospective, controlled trial that assessed the effectiveness of a multidisciplinary DM outreach service in improving the quality of care for patients with type 2 DM in rural communities. The DOVE study was designed to improve care for rural patients with DM, as access to a high level of organized care is limited in rural regions. The primary objective of the DOVE study was to assess the impact of the intervention in improving the metabolic control of people with DM, with attention to blood glucose and lipid levels and BP.14,15 Further details regarding study design and rationale are outlined elsewhere.14,15 Study Sample
We collected information from a cohort of patients with type 2 DM living in 2 comparable and geographically adjacent rural regions in northern Alberta. These regions were randomly allocated, using a coin toss, to be the intervention or the control region. The intervention region had a population of 20,000 residents, 17 physicians, and 1 full-time and 2 part-time DM educators. The control region had a 599
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population of 25,000 residents, 22 physicians, and 1 part-time DM educator. Both regions were about a 6-hour drive from the nearest secondary- or tertiarycare referral center. These regions were selected for study because they were anticipated to be comparable in patient demographic characteristics and accessibility to health care services and they were believed to be representative of the rural, northern Alberta population.14,15 Patients aged ≥20 years were recruited, using identical methods in both regions, via referrals from DM health care professionals, local pharmacists, primary care physicians, and self-referral. Patients were included if they had type 2 DM, provided written informed consent, and had sufficient English literacy to answer questionnaires. We excluded individuals unable or unwilling to provide consent or with shortened life expectancy.14,15 Sociodemographic and clinical data were collected at the time of enrollment into the DOVE study.15 The data for the present analysis were collected at the time of study entry. The protocol for the DOVE study was approved by the Health Research Ethics Board at the University of Alberta (Edmonton, Alberta, Canada). Data were collected from April 2000 to October 2000. Trained study coordinators conducted inperson interviews and collected detailed information from patients.15 A complete medical history, including medication use, was compiled from patient selfreport and pharmacy records. Standardized physical assessments were completed at baseline by local study coordinators; measurements of body weight, height, and BP (mean of 3 consecutive readings) were recorded. Generic health-related quality of life was assessed using the Medical Outcomes Study 12-Item Short Form (MOS SF-12),16 which was previously validated in this sample of patients with type 2 DM.17 Medication histories were compiled through a combination of patient histories, medical charts, “brownbag” assessments (in which patients brought their medications to the clinic for review by local coordinators), and local pharmacy records.15,18 Data Analysis
Hypertension was defined as systolic BP (SBP)/ diastolic BP (DBP) >130/>85 mm Hg and/or current use of pharmacotherapy for hypertension. Treatment gaps were determined by comparing the current use 600
(or lack thereof) of antihypertensive pharmacotherapy in patients with (or without) a BP target of ≤130/≤85 mm Hg, according to the Canadian Diabetes Association’s 1998 Clinical Practice Guidelines for the Management of Diabetes in Canada,19 as these were the guidelines available at the time of the DOVE study. Because more recent guidelines20 have lowered recommended BP targets, sensitivity analysis was performed to compare the differences in magnitude of the treatment gaps between treatment BP targets of ≤130/≤80 mm Hg and ≤130/≤85 mm Hg, which is the target specified by the more recent recommendations.20 Multivariate logistic regression analyses were employed to determine the association between the use of antihypertensive agents and a set of independent predictor variables, including sociodemographic (age, sex, and aboriginal status) and clinical (body mass index [BMI], BP, duration of DM, number of antihypertensive medications, smoking status, use of nitrates as a marker of symptomatic coronary artery disease, and mental and physical health quality-of-life scores as measured using the MOS SF-1216) characteristics. Smoking status was defined as being a past/ current smoker versus a nonsmoker. Symptomatic coronary artery disease was based on the prescribing of nitrates.21,22 P < 0.05 was considered to be statistically significant; unadjusted and adjusted odds ratios (aORs) and their 95% CIs are also reported. RESULTS
A total of 392 patients (229 women, 163 men; mean [SD] age, 62.3 [12.5] years) with type 2 DM were included in this analysis (Table I).14,15 Patients had a mean (SD) duration of diabetes of 8.3 (8.5) years and a mean (SD) BMI of 32.9 (6.9) kg/m2. A total of 241 patients (61.2%) were smokers (ie, past or current). Median SBP (interquartile range [IQR]) was 130.0 (26.0) mm Hg; median DBP was 76.0 (16.0) mm Hg. Patients were receiving a median (IQR) of 1.0 (2.0) antihypertensive medications; thus, the majority of the sample was receiving a monotherapy regimen. The prevalence of hypertension, as previously defined, was 75.8% (297/392); 222 (56.6%) patients considered hypertensive had a BP above the recommended target of ≤130/≤85 mm Hg. From medication histories, 157 (40.1%) of all patients were not receiving any pharmacotherapy for hypertension at
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Table I. Baseline sociodemographic and clinical characteristics of study patients.*
Characteristic
All Patients (N = 392)
Receiving Antihypertensives (n = 235)
Not Receiving Antihypertensives (n = 157)
Age, y Mean (SD) Range
62.3 (12.5) 24–90
65.83 (10.59) 35–90
57.36 (13.41) 24–89
Sex, no. (%) Women Men
229 (58.4) 163 (41.6)
148 (63.0) 87 (37.0)
P
<0.001 0.02
Aboriginal status, no. (%) Body mass index, mean (SD), kg/m2
94 (24.0)
49 (52.1)
81 (51.6) 76 (48.4) 45 (28.7)
<0.001
32.9 (6.9)
33.4 (7.0)
31.6 (6.6)
130.0 (26.0) 76.0 (16.0)
134.0 (26.0) 78.0 (16.0)
127.0 (22.0) 74.0 (16.5)
<0.001 0.112
Duration of diabetes, mean (SD), y
8.3 (8.5)
8.75 (8.80)
6.27 (6.89)
0.004
No. of antihypertensive medications, median (IQR)
1.0 (2.0)
1.0 (2.0)
Blood pressure, median (IQR), mm Hg Systolic Diastolic
History of smoking, no. Current user Past smoker Never smoked
–
0.452
–
(%)† 67 (18.4) 174 (47.8) 123 (33.8)
34 (50.7) 94 (54.0) 91 (74.0)
33 (49.3) 80 (46.0) 32 (26.0)
<0.001
IQR = interquartile range. *Data from the Diabetes Outreach Van Enhancement study (April 2000 to October 2000).14,15 †Data missing from 28 patients.
baseline. Of these untreated patients, 67 (42.7%) were not at the established BP target. Of the 235 (59.9%) patients receiving pharmacotherapy for hypertension, 155 (65.7%) were above the established BP target. Most treated patients (111 [47.0%]) were receiving monotherapy; 82 (34.8%) were receiving dual therapy, 29 (12.3%) were receiving triple therapy, and 13 (5.5%) were receiving ≥4 antihypertensive medications (Figure 1).14,15 Of patients receiving monotherapy, 77 (70.0%) were above BP targets. Of patients receiving dual, triple, and ≥4 medications, 53 (64.5%), 53 (65.5%), and 13 (46.1%), respectively, were above BP targets. Using the more currently suggested BP target of ≤130/≤80 mm Hg, 49.7% of those not receiving pharmacotherapy were not at target, a 7.0% increase in those defined as undertreated using the previously recommended BP target (Figure 2).5,7,14,15,20,23 Patients receiving ≥2 medications follow a similar pattern: a change in BP target results in <1% change
in the treatment gap for those receiving monotherapy. Here, patients receiving 4 antihypertensive medications are most sensitive to the changes in BP target where the treatment gap increases by 23.7%. Prescribing patterns for antihypertensive agents in the present study were generally concordant with the Canadian Hypertension Society Recommendations Working Group’s 2003 Canadian Recommendations for the Management of Hypertension: Therapy.20 Angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin II–receptor blockers (ARBs) were used most frequently as monotherapy (74.0% of patients on monotherapy), followed by calcium channel blockers (CCBs) (13.0%). Low-dose thiazide and beta-blocker use was limited, however, at 6.0% and 8.4%, respectively. The most frequent combination therapy was an ACE inhibitor plus a CCB (9% of all therapy patterns), followed by an ACE inhibitor plus a loop diuretic (5%). After controlling for SBP, male sex (aOR, 2.17; 95% CI, 1.17–4.03), older age (aOR, 1.80 per decade; 601
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Monotherapy Dual therapy Triple therapy ≥4 Medications
5.5% 12.3%
47.0%
34.8%
Figure 1. Percentage of patients receiving antihypertensive therapy regimens at baseline. (Data from the Diabetes Outreach Van Enhancement study [April 2000 to October 2000].14,15)
BP controlled BP not controlled
45 40 35
% Patients
30 25 20 15 10 5 0 ≤130/85 ≤130/80 ≤130/85 ≤130/80 ≤130/85 ≤130/80 ≤130/85 ≤130/80 ≤130/85 ≤130/80 No HTN Therapy
Monotherapy
Dual Therapy
Triple Therapy
≥4 Medications
Therapy Pattern with BP Target
Figure 2. Hypertension (HTN) treatment gaps with varied blood pressure (BP) targets (expressed as millimeters of mercury). (Data from the Diabetes Outreach Van Enhancement study [April 2000 to October 2000].14,15) 602
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95% CI, 1.51–2.09), lower self-reported physical health (assessed using the physical component summary of the MOS SF-12; aOR, 0.68; 95% CI, 0.41–0.96), higher BMI (aOR, 1.05; 95% CI, 1.01–1.10), and past/current smoking (aOR, 1.95; 95% CI, 1.01–3.76) were all significantly associated with a lack of treatment for hypertension (Table II).14–16 Aboriginal people appeared to be more likely to be receiving antihypertensive therapy (aOR, 1.96; 95% CI, 0.93–4.11), although this aOR was not statistically significant. This observation may be of interest because 26.6% of the sample was aboriginal. DISCUSSION
Research suggests that many treatment opportunities exist in the management of increased cardiovascular risk for people with type 2 DM.8,9,13 Aggressive management of hypertension in patients with DM is perhaps one of the most important treatment strategies aimed at reducing long-term complications in this population.7 Although mean baseline BP measurements were close to recommended targets, there were opportunities to start treatment in many patients and opportunities to intensify treatment in those already being treated for elevated BP in this sample of patients with type 2 DM in rural areas. Treatment gaps were present regardless of the therapy pattern, with lack of antihypertensive pharmacotherapy and suboptimal monotherapy presenting the largest gaps. Com-
Table II.
pounding the treatment gaps for isolated hypertension management, the presence of other modifiable risk factors (ie, smoking and BMI) were also associated with a lack of pharmacotherapy, regardless of SBP. Furthermore, there appeared to be a treatment bias, with younger and female patients being less likely to receive antihypertensive therapy or be adherent to prescribed therapy. This is particularly concerning, given the elevated cardiovascular risk for women with DM and their poorer prognosis compared with that of women not having DM.24–26 For those receiving monotherapy, the large treatment gap (ie, 70% not achieving BP target) may suggest a resistance by treating physicians to proceed to combination therapy. It may be possible for clinicians to consider maximizing monotherapy dosages before advancing to combination therapy. Recent recommendations5,20 support use of combination therapy, where individual drug dosages may be kept low and additional medications added to minimize side-effect profiles and achieve BP lowering through multiple mechanisms. In addition, literature suggests that those with DM may require ≥3 medications to achieve the recommended BP target.5,7,23,27 This may be seen in the present study, where the proportion of people with BP control increases as the number of antihypertensive medications increase. When antihypertensive medications were prescribed, the choice of therapy was relatively concordant with guidelines.20 ACE inhibitors and/or ARBs
Independent risk factors of receiving antihypertensive therapy.* Risk Factor
aOR
95% CI
Age (10-year intervals)† Male† Aboriginal status BMI, kg/m2† SBP (10–mm Hg interval)† Duration of diabetes Smoker† Mental health (MCS-12) (10-point interval) Physical health (PCS-12) (10-point interval)†
1.80 2.17 1.96 1.05 1.23 1.02 1.95 0.89 0.68
1.51–2.09 1.17–4.03 0.93–4.11 1.01–1.10 1.06–1.41 0.98–1.06 1.01–3.76 0.59–1.18 0.41–0.96
aOR = adjusted odds ratio; BMI = body mass index; SBP = systolic blood pressure; MCS-12 and PCS-12 = the mental and physical health component summaries of the Medical Outcomes Study 12-Item Short Form.16 *Multivariate logistic regression analysis. n = 270 (due to missing data on covariates). Data from the Diabetes Outreach Van Enhancement study (April 2000 to October 2000).14,15 †P < 0.05.
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were most commonly used as monotherapy (74%), followed by a combination of an ACE inhibitor and a CCB (9%). However, use of low-dose thiazides (6%) and beta-blockers (3%) may be lower than expected. Evidence suggests that thiazide-type diuretic medications are a credible choice for monotherapy and a cost-effective alternative in hypertension management, and that beta-blockers should be avoided only in those with severely labile blood sugar levels or hypoglycemic unawareness.7,28–30 Given the timing of the data collection (ie, 2000) we felt it appropriate to assess the implementation of 1998 clinical practice guidelines for the management of diabetes. Canadian guidelines for treating hypertension are now revisited annually; therefore, we also considered the patterns of practice relative to current 2003 guidelines for hypertension management in people with DM.20 As would be expected, lower BP targets result in a significant increase in treatment opportunities for those receiving pharmacotherapy. It should be recognized that this analysis was crosssectional, thereby limiting conclusions on the progressive management of hypertension. Prescribing trends vary longitudinally, and the time from initiation of therapy to changes in BP readings may not be similar for all patients; therefore, causality cannot be assessed. For these reasons, therapy regimens and BP targets may not be accurately correlated because BP targets may not have yet been realized in patients with new therapy. Given that the median duration of DM in this population was 8.3 years, this situation is unlikely in the vast majority of the study sample. There are other limitations that should be considered. First, we must recognize that other patient factors such as nonadherence, low income or education, or inaccessibility to pharmacies may affect the results. Next, we did not ascertain whether people had a formal diagnosis of hypertension, nor did we have information regarding diet, exercise, or other lifestyle measures. Also, we must recognize that we are not aware of the intended use for each medication being prescribed. Medications may also be used for their renal protective function, cardiac protective or treatment function, or for headache/migraine prophylaxis as opposed to specifically for hypertension. Because we expect that these clinical uses are limited, it is anticipated that analysis of indication would not sig604
nificantly affect the treatment gap results. Patientspecific clinical histories would be required to know for certain, however. Some might consider that the present examination of hypertension trends in a sample of volunteers willing to be enrolled in a study might bias the results. We expect, however, that this bias led us to underestimate the extent and magnitude of the undertreatment of hypertension. Finally, the study sample was drawn from 2 adjacent rural regions in Canada, and thus our results may not be generalizable to urban populations or populations outside of Canada. CONCLUSIONS
Overall, hypertension treatment gaps were present in this sample of rural Canadian patients with type 2 DM, relative to the recommendations from currently available clinical practice guidelines. Cardiovascular risk appears to be underestimated in these patients with type 2 DM, particularly in younger patients, women, and those with multiple non-DM risk factors. Suggestions for future practice efforts include more aggressive strategies in initiating hypertension pharmacotherapy in people with DM in general; targeting certain subgroups of people with DM, such as women; and/or more prompt progression to combination pharmacotherapies in those already treated for hypertension. ACKNOWLEDGMENTS
Funding for the DOVE study was provided by the Canadian Diabetes Association (Toronto, Ontario, Canada), Caritas Health Group (Edmonton, Alberta, Canada), and the Institute of Health Economics (Edmonton). The present study was supported by a New Emerging Team grant to the Alliance for Canadian Health Outcomes Research in Diabetes (Edmonton). This grant is sponsored by the Canadian Diabetes Association (Toronto); the Heart and Stroke Foundation of Canada (Ottawa, Ontario, Canada); The Kidney Foundation of Canada (Ottawa); the Canada Institutes of Health Research (CIHR)–Institute of Nutrition, Metabolism and Diabetes (Ottawa); and the CIHR–Institute of Circulatory and Respiratory Health (Ottawa). Drs. Majumdar and Johnson are Population Health Investigators of the Alberta Heritage Foundation for Medical Research. In addition, Dr. Majumdar is a New Investigator of Canadian Institutes of Health Research,
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and Dr. Johnson holds a Canada Research Chair in Diabetes Outcomes Research. We acknowledge the support of the Epidemiology Coordinating and Research Center (EPICORE), Division of Cardiology, University of Alberta (Edmonton), for data management. REFERENCES 1. Blanchard JF, Ludwig S, Wajda A, et al. Incidence and prevalence of diabetes in Manitoba, 1986–1991. Diabetes Care. 1996;19:807–811. 2. Health Canada (2003 Jan 17) Facts & Figures. Available at: http://www.hc-sc.gc.ca/pphb-dgspsp/ccdpc-cpcmc/ diabete/english/facts/index.html. Accessed April 28,2003. 3. Haffner SM, Lehto S, Ronnemaa T, et al. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. N Engl J Med. 1998;339:229– 234. 4. Gu K, Cowie CC, Harris MI. Diabetes and decline in heart disease mortality in US adults. JAMA. 1999; 281:1291–1297. 5. Arauz-Pacheo C, Parrott MA, Raskin P, for the American Diabetes Association. Treatment of hypertension in adults with diabetes. Diabetes Care. 2003;26 (Suppl 1):S80–S82. 6. Simpson SH, Corabian P, Jacobs P, Johnson JA. The cost of major comorbidity in people with diabetes mellitus. CMAJ. 2003;168:1661–1667. 7. Vijan S, Hayward RA. Treatment of hypertension in type 2 diabetes mellitus: Blood pressure goals, choice of agents, and setting priorities in diabetes care. Ann Intern Med. 2003;138:593–602. 8. Grant RW, Cagliero E, Murphy-Sheehy P, et al. Comparison of hyperglycemia, hypertension, and hypercholesterolemia management in patients with type 2 diabetes. Am J Med. 2002;112:603–609. 9. McFarlane SI, Jacober SJ, Winer N, et al. Control of cardiovascular risk factors in patients with diabetes and hypertension at urban academic medical centers. Diabetes Care. 2002;25:718–723. 10. Yale JF, Lambert J, Hamel R. Management of hyperglycemia and cardiovascular disease risk factors: Epidemiological survey in patients with type 2 diabetes. Can J Diabetes. 2003;27:331. Abstract. 11. Yawn BP, Casey M, Hebert P. The rural health care workforce implications of practice guideline implementation. Med Care. 1999;37:259–269.
12. Bell RA, Camacho F, Goonan K, et al. Quality of diabetes care among low-income patients in North Carolina. Am J Prev Med. 2001;21:124–131. Toth EL, Majumdar SR, Guirguis LM, et al. 13. Compliance with clinical practice guidelines for type 2 diabetes in rural patients: Treatment gaps and opportunities for improvement. Pharmacotherapy. 2003;23: 659–665. 14. Majumdar SR, Guirguis LM, Toth EL, et al. Controlled trial of a multifaceted intervention for improving quality of care for rural patients with type 2 diabetes. Diabetes Care. 2003;26:3061–3066. 15. Majumdar SR, Johnson JA, Guirguis LM, et al. Rationale and design for the DOVE study: A prospective, controlled trial of an intervention to improve care for patients with diabetes in rural communities. Can J Diabetes Care. 2001;25:173–179. 16. Ware J Jr, Kosinski M, Keller SD. A 12-item ShortForm Health Survey: Construction of scales and preliminary tests of reliability and validity. Med Care. 1996;34:220–233. 17. Maddigan SL, Feeny DH, Johnson JA, for the DOVE Investigators. Construct validity of the RAND-12 and Health Utilities Index Mark 2 and Mark 3 in type 2 diabetes. Qual Life Res. In press. 18. Schapansky LM, Johnson JA, Majumdar SR, et al. The burden of pharmacotherapy for patients with type 2 diabetes in northern Alberta—data from the DOVE study. Can J Clin Pharmacol. 2001;8:22. 19. Meltzer S, Leiter L, Daneman D, et al. 1998 clinical practice guidelines for the management of diabetes in Canada. Canadian Diabetes Association. CMAJ. 1998; 159(Suppl 8):S1–S29. 20. Canadian Hypertension Society Recommendations Working Group. The 2003 Canadian recommendations for the management of hypertension. Available at: http://www.chs.md/Documentation/Recommendations 2003.pdf. Accessed May 15, 2003. 21. Tsuyuki RT, Olson KL, Teo KK. Nitroglycerin as an indicator for the presence of coronary heart disease. Can Pharm J. 1999;132:32–36. 22. Connolly P, Cupples ME, Cuene-Grandidier H, et al. The importance of validating the diagnosis of coronary heart disease when measuring secondary prevention: A cross-sectional study in general practice. Pharmacoepidemiol Drug Saf. 2002;11:311–317. 23. Chobanian AV, Bakris GL, Black HR, et al, for the National Heart, Lung, and Blood Institute Joint 605
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National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National High Blood Pressure Education Program Coordinating Committee. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report [published correction appears in JAMA. 2003;290:197]. JAMA. 2003;289:2560–2572. 24. Chin MH, Goldman L. Gender differences in 1-year survival and quality of life among patients admitted with congestive heart failure. Med Care. 1998;36:1033– 1046. 25. Shumaker SA, Brooks MM, Schron EB, et al. Gender differences in health-related quality of life among postmyocardial infarction patients: Brief report. CAST Investigators. Cardiac Arrhythmia Suppression Trials. Womens Health. 1997;3:53–60. 26. Vaccarino V, Krumholz HM, Yarzebski J, et al. Sex differences in two-year mortality after hospital discharge
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for myocardial infarction. Ann Intern Med. 2001;134: 173–181. Tight blood pressure control and risk of macrovascular and microvascular complications in type 2 diabetes: UKPDS 38. UK Prospective Diabetes Study Group. BMJ. 1998;317:703–713. ALLHAT Collaborative Research Group. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). JAMA. 2002;288:2981–2997. Psaty BM, Smith NL, Siscovick DS, et al. Health outcomes associated with antihypertensive therapies used as first-line agents. A systematic review and metaanalysis. JAMA. 1997;277:739–745. Majumdar SR. Beta-blockers for the treatment of hypertension in patients with diabetes: Exploring the contraindication myth. Cardiovasc Drugs Ther. 1999;13:435–439.
Address correspondence to: Jeffrey A. Johnson, PhD, Institute of Health Economics, #1200–10405 Jasper Avenue, Edmonton, Alberta, Canada T5J 3N4. E-mail: [email protected] 606
Brief Report
Treatment Gaps for Hypertension Management in Rural Canadian Patients with Type 2 Diabetes Mellitus Alison L. Supina, BScPharm,1,4 Lisa M. Guirguis, BScPharm, MSc,1 Sumit R. Majumdar, MD, MPH, FRCPC,1,2 Richard Z. Lewanczuk, MD, PhD, FRCPC,2 T.K. Lee, MD, FRCPC,2,3 Ellen L. Toth, MD, FRCPC,1,2 and Jeffrey A. Johnson, PhD1,4 1Alliance
for Canadian Health Outcomes Research in Diabetes, Institute of Health Economics, 2Department of Medicine, University of Alberta, 3Department of Medicine, Grey Nuns Hospital, and 4Department of Public Health Sciences, University of Alberta, Edmonton, Alberta, Canada
ABSTRACT
Background: There were a reported 2.2 million Canadians living with diabetes mellitus (DM) in 2002, of whom 1.98 million (90.0%) had type 2 DM. In addition, there are ~60,000 new cases of type 2 DM diagnosed in Canada each year. However, the research shows that evidence and guidelines for management of hypertension in DM are not always translated into clinical practice. In rural areas, factors affecting implementation of recommendations and/or guidelines are less well understood, although some studies suggest that urban practices provide higher quality of care overall than rural areas. Objective: The goal of this study was to describe the patterns of medication use for hypertension for patients with type 2 DM in rural northern Alberta, Canada. We also tried to identify treatment gaps and opportunities for prescribing antihypertensives relative to the Canadian Diabetes Association’s 1998 Clinical Practice Guidelines for the Management of Diabetes in Canada and the Canadian Hypertension Society Recommendations Working Group’s 2003 Canadian Recommendations for the Management of Hypertension: Therapy. Methods: This study was conducted at the Institute of Health Economics and the University of Alberta (Edmonton, Alberta, Canada). We collected information from a cohort of patients aged ≥20 years with type 2 DM living in 2 adjacent rural regions of northern Alberta, Canada, at the time of enrollment in a diabetes care quality-improvement program as part of the Diabetes Outreach Van Enhancement (DOVE) study. Treatment gaps were determined by comparing antihypertensive pharmacotherapy with a blood pressure (BP) target of ≤130/≤85 mm Hg. We used multivariate regression analyses to determine the associations between sociodemographic and clinical characteristics and treatment gaps. Results: A total of 392 patients (229 women, 164 men; mean [SD] age, 62.3 [12.5] years) with type 2 DM were included in this analysis. Patients had a mean (SD) duration of diabetes of 8.3 (8.5) years. A total of 75.8% (297/392) of the study population had hypertension, and most (236/392 [60.2%]) were receiving some pharmacotherapy. Treatment gaps were present; 42.7% (n = 67) of patients not receiving pharmacotherapy for hypertension were above the established BP targets. For patients receiving monotherapy, 70% were not at BP targets. For patients receiving dual, triple, and ≥4 medications, 65%, 66%, and 46%, respectively, were not at BP targets. After controlling for systolic blood pressure, male sex (adjusted odds ratio [aOR], 2.17; 95% CI, 1.17–4.03), This article was presented in poster form at the annual meeting of the Canadian Association of Population Therapeutics; Toronto, Ontario, Canada; April 14–16, 2002, and in poster form at the annual meeting of the Canadian Diabetes Association; Ottawa, Ontario, Canada, October 16–18, 2003. Accepted for publication January 21, 2004. Printed in the USA. Reproduction in whole or part is not permitted. 0149-2918/04/$19.00
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older age (aOR, 1.80 per decade; 95% CI, 1.51–2.09), lower self-reported physical health (aOR, 0.68; 95% CI, 0.41–0.96), higher body mass index (aOR, 1.05; 95% CI, 1.01–1.10), and past/current smoking (aOR, 1.95; 95% CI, 1.01–3.76) were all significantly associated with a lack of treatment for hypertension. Conclusions: Treatment gaps in the management of hypertension exist in these rural Canadian patients with type 2 DM. Cardiovascular risk may be underestimated in these patients, particularly among younger patients and women, and those with multiple non-DM risk factors. These are patient subgroups that should be targeted as opportunities to improve hypertension management at the population level. (Clin Ther. 2004;26:598–606) Copyright © 2004 Excerpta Medica, Inc. Key words: type 2 diabetes, hypertension, guidelines, treatment gaps.
pressure (BP) also reduces the risk for microvascular complications—such as vision impairment and endstage renal disease—by as much as 10%.7 Despite this strong proof, research also shows that evidence and guidelines for management of hypertension in DM are not always translated into clinical practice. Recent studies in urban centers in the United States7–10 suggest that ~60% to 90% of individuals with type 2 DM are not at BP targets. In rural areas, factors affecting the implementation of practice recommendations and/or guidelines are less well understood, although some studies11–13 suggest that urban practices provide a higher quality of care overall than rural areas. The purpose of the current study was to describe the patterns of antihypertensive medication use by patients with type 2 DM in rural, northern Alberta, Canada. We also tried to identify treatment gaps and opportunities for prescribing antihypertensive medication in type 2 DM relative to guidelines for hypertension management.
INTRODUCTION
PATIENTS AND METHODS The Diabetes Outreach Van Enhancement Study
The prevalence of diabetes mellitus (DM) is increasing rapidly.1,2 Health Canada,2 the federal department responsible for helping the people of Canada maintain and improve their health, reported that 2.2 million Canadians were living with DM in 2002, 1.98 million (90.0%) of whom had type 2 DM. In addition, ~60,000 new cases of type 2 DM are diagnosed in Canada each year.2 This rapid increase in prevalence may be a result of enhanced screening and disease awareness; however, responsibility is more likely to lie with an aging population and lifestyle considerations. Cardiovascular disease is the leading cause of death in patients with type 2 DM and is associated with significant morbidity and mortality.3,4 Also, the direct medical costs associated with macrovascular complications are much greater than those associated with microvascular complications.5,6 Studies involving intensive treatment of multiple risk factors to prevent macro- and microvascular complications consistently show that aggressive treatment of hypertension can result in up to 50% decreased risk reductions in cardiovascular morbidity and mortality, more so than control of blood glucose and cholesterol levels.7 Vijan and Hayward7 suggested that aggressive treatment of elevated blood
The Diabetes Outreach Van Enhancement (DOVE) study14,15 was a prospective, controlled trial that assessed the effectiveness of a multidisciplinary DM outreach service in improving the quality of care for patients with type 2 DM in rural communities. The DOVE study was designed to improve care for rural patients with DM, as access to a high level of organized care is limited in rural regions. The primary objective of the DOVE study was to assess the impact of the intervention in improving the metabolic control of people with DM, with attention to blood glucose and lipid levels and BP.14,15 Further details regarding study design and rationale are outlined elsewhere.14,15 Study Sample
We collected information from a cohort of patients with type 2 DM living in 2 comparable and geographically adjacent rural regions in northern Alberta. These regions were randomly allocated, using a coin toss, to be the intervention or the control region. The intervention region had a population of 20,000 residents, 17 physicians, and 1 full-time and 2 part-time DM educators. The control region had a 599
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population of 25,000 residents, 22 physicians, and 1 part-time DM educator. Both regions were about a 6-hour drive from the nearest secondary- or tertiarycare referral center. These regions were selected for study because they were anticipated to be comparable in patient demographic characteristics and accessibility to health care services and they were believed to be representative of the rural, northern Alberta population.14,15 Patients aged ≥20 years were recruited, using identical methods in both regions, via referrals from DM health care professionals, local pharmacists, primary care physicians, and self-referral. Patients were included if they had type 2 DM, provided written informed consent, and had sufficient English literacy to answer questionnaires. We excluded individuals unable or unwilling to provide consent or with shortened life expectancy.14,15 Sociodemographic and clinical data were collected at the time of enrollment into the DOVE study.15 The data for the present analysis were collected at the time of study entry. The protocol for the DOVE study was approved by the Health Research Ethics Board at the University of Alberta (Edmonton, Alberta, Canada). Data were collected from April 2000 to October 2000. Trained study coordinators conducted inperson interviews and collected detailed information from patients.15 A complete medical history, including medication use, was compiled from patient selfreport and pharmacy records. Standardized physical assessments were completed at baseline by local study coordinators; measurements of body weight, height, and BP (mean of 3 consecutive readings) were recorded. Generic health-related quality of life was assessed using the Medical Outcomes Study 12-Item Short Form (MOS SF-12),16 which was previously validated in this sample of patients with type 2 DM.17 Medication histories were compiled through a combination of patient histories, medical charts, “brownbag” assessments (in which patients brought their medications to the clinic for review by local coordinators), and local pharmacy records.15,18 Data Analysis
Hypertension was defined as systolic BP (SBP)/ diastolic BP (DBP) >130/>85 mm Hg and/or current use of pharmacotherapy for hypertension. Treatment gaps were determined by comparing the current use 600
(or lack thereof) of antihypertensive pharmacotherapy in patients with (or without) a BP target of ≤130/≤85 mm Hg, according to the Canadian Diabetes Association’s 1998 Clinical Practice Guidelines for the Management of Diabetes in Canada,19 as these were the guidelines available at the time of the DOVE study. Because more recent guidelines20 have lowered recommended BP targets, sensitivity analysis was performed to compare the differences in magnitude of the treatment gaps between treatment BP targets of ≤130/≤80 mm Hg and ≤130/≤85 mm Hg, which is the target specified by the more recent recommendations.20 Multivariate logistic regression analyses were employed to determine the association between the use of antihypertensive agents and a set of independent predictor variables, including sociodemographic (age, sex, and aboriginal status) and clinical (body mass index [BMI], BP, duration of DM, number of antihypertensive medications, smoking status, use of nitrates as a marker of symptomatic coronary artery disease, and mental and physical health quality-of-life scores as measured using the MOS SF-1216) characteristics. Smoking status was defined as being a past/ current smoker versus a nonsmoker. Symptomatic coronary artery disease was based on the prescribing of nitrates.21,22 P < 0.05 was considered to be statistically significant; unadjusted and adjusted odds ratios (aORs) and their 95% CIs are also reported. RESULTS
A total of 392 patients (229 women, 163 men; mean [SD] age, 62.3 [12.5] years) with type 2 DM were included in this analysis (Table I).14,15 Patients had a mean (SD) duration of diabetes of 8.3 (8.5) years and a mean (SD) BMI of 32.9 (6.9) kg/m2. A total of 241 patients (61.2%) were smokers (ie, past or current). Median SBP (interquartile range [IQR]) was 130.0 (26.0) mm Hg; median DBP was 76.0 (16.0) mm Hg. Patients were receiving a median (IQR) of 1.0 (2.0) antihypertensive medications; thus, the majority of the sample was receiving a monotherapy regimen. The prevalence of hypertension, as previously defined, was 75.8% (297/392); 222 (56.6%) patients considered hypertensive had a BP above the recommended target of ≤130/≤85 mm Hg. From medication histories, 157 (40.1%) of all patients were not receiving any pharmacotherapy for hypertension at
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Table I. Baseline sociodemographic and clinical characteristics of study patients.*
Characteristic
All Patients (N = 392)
Receiving Antihypertensives (n = 235)
Not Receiving Antihypertensives (n = 157)
Age, y Mean (SD) Range
62.3 (12.5) 24–90
65.83 (10.59) 35–90
57.36 (13.41) 24–89
Sex, no. (%) Women Men
229 (58.4) 163 (41.6)
148 (63.0) 87 (37.0)
P
<0.001 0.02
Aboriginal status, no. (%) Body mass index, mean (SD), kg/m2
94 (24.0)
49 (52.1)
81 (51.6) 76 (48.4) 45 (28.7)
<0.001
32.9 (6.9)
33.4 (7.0)
31.6 (6.6)
130.0 (26.0) 76.0 (16.0)
134.0 (26.0) 78.0 (16.0)
127.0 (22.0) 74.0 (16.5)
<0.001 0.112
Duration of diabetes, mean (SD), y
8.3 (8.5)
8.75 (8.80)
6.27 (6.89)
0.004
No. of antihypertensive medications, median (IQR)
1.0 (2.0)
1.0 (2.0)
Blood pressure, median (IQR), mm Hg Systolic Diastolic
History of smoking, no. Current user Past smoker Never smoked
–
0.452
–
(%)† 67 (18.4) 174 (47.8) 123 (33.8)
34 (50.7) 94 (54.0) 91 (74.0)
33 (49.3) 80 (46.0) 32 (26.0)
<0.001
IQR = interquartile range. *Data from the Diabetes Outreach Van Enhancement study (April 2000 to October 2000).14,15 †Data missing from 28 patients.
baseline. Of these untreated patients, 67 (42.7%) were not at the established BP target. Of the 235 (59.9%) patients receiving pharmacotherapy for hypertension, 155 (65.7%) were above the established BP target. Most treated patients (111 [47.0%]) were receiving monotherapy; 82 (34.8%) were receiving dual therapy, 29 (12.3%) were receiving triple therapy, and 13 (5.5%) were receiving ≥4 antihypertensive medications (Figure 1).14,15 Of patients receiving monotherapy, 77 (70.0%) were above BP targets. Of patients receiving dual, triple, and ≥4 medications, 53 (64.5%), 53 (65.5%), and 13 (46.1%), respectively, were above BP targets. Using the more currently suggested BP target of ≤130/≤80 mm Hg, 49.7% of those not receiving pharmacotherapy were not at target, a 7.0% increase in those defined as undertreated using the previously recommended BP target (Figure 2).5,7,14,15,20,23 Patients receiving ≥2 medications follow a similar pattern: a change in BP target results in <1% change
in the treatment gap for those receiving monotherapy. Here, patients receiving 4 antihypertensive medications are most sensitive to the changes in BP target where the treatment gap increases by 23.7%. Prescribing patterns for antihypertensive agents in the present study were generally concordant with the Canadian Hypertension Society Recommendations Working Group’s 2003 Canadian Recommendations for the Management of Hypertension: Therapy.20 Angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin II–receptor blockers (ARBs) were used most frequently as monotherapy (74.0% of patients on monotherapy), followed by calcium channel blockers (CCBs) (13.0%). Low-dose thiazide and beta-blocker use was limited, however, at 6.0% and 8.4%, respectively. The most frequent combination therapy was an ACE inhibitor plus a CCB (9% of all therapy patterns), followed by an ACE inhibitor plus a loop diuretic (5%). After controlling for SBP, male sex (aOR, 2.17; 95% CI, 1.17–4.03), older age (aOR, 1.80 per decade; 601
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Monotherapy Dual therapy Triple therapy ≥4 Medications
5.5% 12.3%
47.0%
34.8%
Figure 1. Percentage of patients receiving antihypertensive therapy regimens at baseline. (Data from the Diabetes Outreach Van Enhancement study [April 2000 to October 2000].14,15)
BP controlled BP not controlled
45 40 35
% Patients
30 25 20 15 10 5 0 ≤130/85 ≤130/80 ≤130/85 ≤130/80 ≤130/85 ≤130/80 ≤130/85 ≤130/80 ≤130/85 ≤130/80 No HTN Therapy
Monotherapy
Dual Therapy
Triple Therapy
≥4 Medications
Therapy Pattern with BP Target
Figure 2. Hypertension (HTN) treatment gaps with varied blood pressure (BP) targets (expressed as millimeters of mercury). (Data from the Diabetes Outreach Van Enhancement study [April 2000 to October 2000].14,15) 602
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95% CI, 1.51–2.09), lower self-reported physical health (assessed using the physical component summary of the MOS SF-12; aOR, 0.68; 95% CI, 0.41–0.96), higher BMI (aOR, 1.05; 95% CI, 1.01–1.10), and past/current smoking (aOR, 1.95; 95% CI, 1.01–3.76) were all significantly associated with a lack of treatment for hypertension (Table II).14–16 Aboriginal people appeared to be more likely to be receiving antihypertensive therapy (aOR, 1.96; 95% CI, 0.93–4.11), although this aOR was not statistically significant. This observation may be of interest because 26.6% of the sample was aboriginal. DISCUSSION
Research suggests that many treatment opportunities exist in the management of increased cardiovascular risk for people with type 2 DM.8,9,13 Aggressive management of hypertension in patients with DM is perhaps one of the most important treatment strategies aimed at reducing long-term complications in this population.7 Although mean baseline BP measurements were close to recommended targets, there were opportunities to start treatment in many patients and opportunities to intensify treatment in those already being treated for elevated BP in this sample of patients with type 2 DM in rural areas. Treatment gaps were present regardless of the therapy pattern, with lack of antihypertensive pharmacotherapy and suboptimal monotherapy presenting the largest gaps. Com-
Table II.
pounding the treatment gaps for isolated hypertension management, the presence of other modifiable risk factors (ie, smoking and BMI) were also associated with a lack of pharmacotherapy, regardless of SBP. Furthermore, there appeared to be a treatment bias, with younger and female patients being less likely to receive antihypertensive therapy or be adherent to prescribed therapy. This is particularly concerning, given the elevated cardiovascular risk for women with DM and their poorer prognosis compared with that of women not having DM.24–26 For those receiving monotherapy, the large treatment gap (ie, 70% not achieving BP target) may suggest a resistance by treating physicians to proceed to combination therapy. It may be possible for clinicians to consider maximizing monotherapy dosages before advancing to combination therapy. Recent recommendations5,20 support use of combination therapy, where individual drug dosages may be kept low and additional medications added to minimize side-effect profiles and achieve BP lowering through multiple mechanisms. In addition, literature suggests that those with DM may require ≥3 medications to achieve the recommended BP target.5,7,23,27 This may be seen in the present study, where the proportion of people with BP control increases as the number of antihypertensive medications increase. When antihypertensive medications were prescribed, the choice of therapy was relatively concordant with guidelines.20 ACE inhibitors and/or ARBs
Independent risk factors of receiving antihypertensive therapy.* Risk Factor
aOR
95% CI
Age (10-year intervals)† Male† Aboriginal status BMI, kg/m2† SBP (10–mm Hg interval)† Duration of diabetes Smoker† Mental health (MCS-12) (10-point interval) Physical health (PCS-12) (10-point interval)†
1.80 2.17 1.96 1.05 1.23 1.02 1.95 0.89 0.68
1.51–2.09 1.17–4.03 0.93–4.11 1.01–1.10 1.06–1.41 0.98–1.06 1.01–3.76 0.59–1.18 0.41–0.96
aOR = adjusted odds ratio; BMI = body mass index; SBP = systolic blood pressure; MCS-12 and PCS-12 = the mental and physical health component summaries of the Medical Outcomes Study 12-Item Short Form.16 *Multivariate logistic regression analysis. n = 270 (due to missing data on covariates). Data from the Diabetes Outreach Van Enhancement study (April 2000 to October 2000).14,15 †P < 0.05.
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were most commonly used as monotherapy (74%), followed by a combination of an ACE inhibitor and a CCB (9%). However, use of low-dose thiazides (6%) and beta-blockers (3%) may be lower than expected. Evidence suggests that thiazide-type diuretic medications are a credible choice for monotherapy and a cost-effective alternative in hypertension management, and that beta-blockers should be avoided only in those with severely labile blood sugar levels or hypoglycemic unawareness.7,28–30 Given the timing of the data collection (ie, 2000) we felt it appropriate to assess the implementation of 1998 clinical practice guidelines for the management of diabetes. Canadian guidelines for treating hypertension are now revisited annually; therefore, we also considered the patterns of practice relative to current 2003 guidelines for hypertension management in people with DM.20 As would be expected, lower BP targets result in a significant increase in treatment opportunities for those receiving pharmacotherapy. It should be recognized that this analysis was crosssectional, thereby limiting conclusions on the progressive management of hypertension. Prescribing trends vary longitudinally, and the time from initiation of therapy to changes in BP readings may not be similar for all patients; therefore, causality cannot be assessed. For these reasons, therapy regimens and BP targets may not be accurately correlated because BP targets may not have yet been realized in patients with new therapy. Given that the median duration of DM in this population was 8.3 years, this situation is unlikely in the vast majority of the study sample. There are other limitations that should be considered. First, we must recognize that other patient factors such as nonadherence, low income or education, or inaccessibility to pharmacies may affect the results. Next, we did not ascertain whether people had a formal diagnosis of hypertension, nor did we have information regarding diet, exercise, or other lifestyle measures. Also, we must recognize that we are not aware of the intended use for each medication being prescribed. Medications may also be used for their renal protective function, cardiac protective or treatment function, or for headache/migraine prophylaxis as opposed to specifically for hypertension. Because we expect that these clinical uses are limited, it is anticipated that analysis of indication would not sig604
nificantly affect the treatment gap results. Patientspecific clinical histories would be required to know for certain, however. Some might consider that the present examination of hypertension trends in a sample of volunteers willing to be enrolled in a study might bias the results. We expect, however, that this bias led us to underestimate the extent and magnitude of the undertreatment of hypertension. Finally, the study sample was drawn from 2 adjacent rural regions in Canada, and thus our results may not be generalizable to urban populations or populations outside of Canada. CONCLUSIONS
Overall, hypertension treatment gaps were present in this sample of rural Canadian patients with type 2 DM, relative to the recommendations from currently available clinical practice guidelines. Cardiovascular risk appears to be underestimated in these patients with type 2 DM, particularly in younger patients, women, and those with multiple non-DM risk factors. Suggestions for future practice efforts include more aggressive strategies in initiating hypertension pharmacotherapy in people with DM in general; targeting certain subgroups of people with DM, such as women; and/or more prompt progression to combination pharmacotherapies in those already treated for hypertension. ACKNOWLEDGMENTS
Funding for the DOVE study was provided by the Canadian Diabetes Association (Toronto, Ontario, Canada), Caritas Health Group (Edmonton, Alberta, Canada), and the Institute of Health Economics (Edmonton). The present study was supported by a New Emerging Team grant to the Alliance for Canadian Health Outcomes Research in Diabetes (Edmonton). This grant is sponsored by the Canadian Diabetes Association (Toronto); the Heart and Stroke Foundation of Canada (Ottawa, Ontario, Canada); The Kidney Foundation of Canada (Ottawa); the Canada Institutes of Health Research (CIHR)–Institute of Nutrition, Metabolism and Diabetes (Ottawa); and the CIHR–Institute of Circulatory and Respiratory Health (Ottawa). Drs. Majumdar and Johnson are Population Health Investigators of the Alberta Heritage Foundation for Medical Research. In addition, Dr. Majumdar is a New Investigator of Canadian Institutes of Health Research,
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and Dr. Johnson holds a Canada Research Chair in Diabetes Outcomes Research. We acknowledge the support of the Epidemiology Coordinating and Research Center (EPICORE), Division of Cardiology, University of Alberta (Edmonton), for data management. REFERENCES 1. Blanchard JF, Ludwig S, Wajda A, et al. Incidence and prevalence of diabetes in Manitoba, 1986–1991. Diabetes Care. 1996;19:807–811. 2. Health Canada (2003 Jan 17) Facts & Figures. Available at: http://www.hc-sc.gc.ca/pphb-dgspsp/ccdpc-cpcmc/ diabete/english/facts/index.html. Accessed April 28,2003. 3. Haffner SM, Lehto S, Ronnemaa T, et al. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. N Engl J Med. 1998;339:229– 234. 4. Gu K, Cowie CC, Harris MI. Diabetes and decline in heart disease mortality in US adults. JAMA. 1999; 281:1291–1297. 5. Arauz-Pacheo C, Parrott MA, Raskin P, for the American Diabetes Association. Treatment of hypertension in adults with diabetes. Diabetes Care. 2003;26 (Suppl 1):S80–S82. 6. Simpson SH, Corabian P, Jacobs P, Johnson JA. The cost of major comorbidity in people with diabetes mellitus. CMAJ. 2003;168:1661–1667. 7. Vijan S, Hayward RA. Treatment of hypertension in type 2 diabetes mellitus: Blood pressure goals, choice of agents, and setting priorities in diabetes care. Ann Intern Med. 2003;138:593–602. 8. Grant RW, Cagliero E, Murphy-Sheehy P, et al. Comparison of hyperglycemia, hypertension, and hypercholesterolemia management in patients with type 2 diabetes. Am J Med. 2002;112:603–609. 9. McFarlane SI, Jacober SJ, Winer N, et al. Control of cardiovascular risk factors in patients with diabetes and hypertension at urban academic medical centers. Diabetes Care. 2002;25:718–723. 10. Yale JF, Lambert J, Hamel R. Management of hyperglycemia and cardiovascular disease risk factors: Epidemiological survey in patients with type 2 diabetes. Can J Diabetes. 2003;27:331. Abstract. 11. Yawn BP, Casey M, Hebert P. The rural health care workforce implications of practice guideline implementation. Med Care. 1999;37:259–269.
12. Bell RA, Camacho F, Goonan K, et al. Quality of diabetes care among low-income patients in North Carolina. Am J Prev Med. 2001;21:124–131. Toth EL, Majumdar SR, Guirguis LM, et al. 13. Compliance with clinical practice guidelines for type 2 diabetes in rural patients: Treatment gaps and opportunities for improvement. Pharmacotherapy. 2003;23: 659–665. 14. Majumdar SR, Guirguis LM, Toth EL, et al. Controlled trial of a multifaceted intervention for improving quality of care for rural patients with type 2 diabetes. Diabetes Care. 2003;26:3061–3066. 15. Majumdar SR, Johnson JA, Guirguis LM, et al. Rationale and design for the DOVE study: A prospective, controlled trial of an intervention to improve care for patients with diabetes in rural communities. Can J Diabetes Care. 2001;25:173–179. 16. Ware J Jr, Kosinski M, Keller SD. A 12-item ShortForm Health Survey: Construction of scales and preliminary tests of reliability and validity. Med Care. 1996;34:220–233. 17. Maddigan SL, Feeny DH, Johnson JA, for the DOVE Investigators. Construct validity of the RAND-12 and Health Utilities Index Mark 2 and Mark 3 in type 2 diabetes. Qual Life Res. In press. 18. Schapansky LM, Johnson JA, Majumdar SR, et al. The burden of pharmacotherapy for patients with type 2 diabetes in northern Alberta—data from the DOVE study. Can J Clin Pharmacol. 2001;8:22. 19. Meltzer S, Leiter L, Daneman D, et al. 1998 clinical practice guidelines for the management of diabetes in Canada. Canadian Diabetes Association. CMAJ. 1998; 159(Suppl 8):S1–S29. 20. Canadian Hypertension Society Recommendations Working Group. The 2003 Canadian recommendations for the management of hypertension. Available at: http://www.chs.md/Documentation/Recommendations 2003.pdf. Accessed May 15, 2003. 21. Tsuyuki RT, Olson KL, Teo KK. Nitroglycerin as an indicator for the presence of coronary heart disease. Can Pharm J. 1999;132:32–36. 22. Connolly P, Cupples ME, Cuene-Grandidier H, et al. The importance of validating the diagnosis of coronary heart disease when measuring secondary prevention: A cross-sectional study in general practice. Pharmacoepidemiol Drug Saf. 2002;11:311–317. 23. Chobanian AV, Bakris GL, Black HR, et al, for the National Heart, Lung, and Blood Institute Joint 605
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National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National High Blood Pressure Education Program Coordinating Committee. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report [published correction appears in JAMA. 2003;290:197]. JAMA. 2003;289:2560–2572. 24. Chin MH, Goldman L. Gender differences in 1-year survival and quality of life among patients admitted with congestive heart failure. Med Care. 1998;36:1033– 1046. 25. Shumaker SA, Brooks MM, Schron EB, et al. Gender differences in health-related quality of life among postmyocardial infarction patients: Brief report. CAST Investigators. Cardiac Arrhythmia Suppression Trials. Womens Health. 1997;3:53–60. 26. Vaccarino V, Krumholz HM, Yarzebski J, et al. Sex differences in two-year mortality after hospital discharge
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Address correspondence to: Jeffrey A. Johnson, PhD, Institute of Health Economics, #1200–10405 Jasper Avenue, Edmonton, Alberta, Canada T5J 3N4. E-mail: [email protected] 606