CLINICAL DIABETES LANDMARK STUDIES Linking Improved Glycemic Control, Quality of Life, and Economics: Evidence to Support Intuition Reviewed by Lawrence Blonde, MD, and Jayant Dey, MD STUDY
SUMMARY Design. This was a double-blind, randomized, placebo-controlled, parallel trial at 62 sites in the United States. Participants. A total of 569 male and female volunteers with type 2 diabetes. Intervention. After a 3-week, single-blind placebo-washout period, participants were randomized to diet and titration with either 5–20 mg of glipizide gastrointestinal therapeutic system (GITS) (n = 377) or placebo (n = 192) for 12 weeks. Outcomes. The main outcomes assessed were changes in HbA1c values in the two groups of patients, as well as an assessment of QOL, days worked, health-related days missed, restricted activity days, and health care utilization. The QOL outcomes included five visual analog scales (VASs) of perceived health, mental and emotional health, self-reported cognitive function, general health perceptions, and symptom distress. These instruments had been described in detail in previous publications from the authors.1,2 There was a monthly assessment of 43 diabetes-specific symptoms. Patients also completed a home diary that included perceived hypoglycemic and hyperglycemic reactions and an immediate subsequent home blood glucose measurement. Results. HbA1c
After 12 weeks, mean (±SE) HbA1c and fasting blood glucose levels decreased
with active therapy (glipizide GITS) versus placebo (7.5 ± 0.1% vs. 9.3 ± 0.1%, and 7.0
± 0.1 mmol/l [126 ± 2 mg/dl] vs. 9.3 ± 0.2 mmol/l [168 ± 4 mg/ dl], respectively; P
< 0.001). QOL treatment differences (SD units) for symptom distress (+0.59; P
< 0.001), general perceived health (+0.36; P = 0.004), cognitive functioning
(+0.34; P = 0.005), and the overall visual analog scale (VAS) (+0.24; P =
0.04) were significantly more favorable for active therapy. Subscales of cognitive acuity
and memory (+0.38; P = 0.002), VAS emotional health (+0.35; P = 0.003),
general health (+0.27; P = 0.01), sleep (+0.26; P = 0.04), depression
(+0.25; P = 0.05), disorientation and detachment (+0.23; P = 0.05), and
vitality (+0.22; P = 0.04) were most affected. Favorable health economic outcomes
for glipizide GITS-treated subjects included higher retained employment measured as the
percentage relative to baseline of the number of subjects who worked >1 day in the
previous week (97 vs. 85%; P < 0.001) and greater group productive capacity
measured as the percentage relative to baseline of the days worked by subjects in each
group in the previous week (99 vs. 87%; P < 0.001). At the end of week 15, 4.8%
of the glipizide GITS-treated patients reported missing >1/2 day of work during the
previous week compared to 10.5% of the placebo-treated subjects. Similarly, the percentage
of patients staying in bed >1/2 day or cutting down on usual activities was less in the
glipizide GITS group (5.5 vs. 8.4% and 7.6 vs. 11.6%, respectively). Using U.S. Bureau of
the Census 1995 estimates of production losses for employed and unemployed males, the
authors calculated fewer absenteeism losses ( $24 vs. $115 per worker per month; P
< 0.001), fewer bed-days losses ($1,539 vs. $1,843 per 1,000 person-days; P =
0.05), and fewer restricted-activity days losses ($2,660 vs. $4,275 per 1,000 person-days;
P = 0.01) for subjects treated with glipizide GITS. Conclusions. Improved glycemic control of type 2 diabetes is associated with substantial short-term symptomatic, QOL, and health economic benefits. COMMENTARY Previous QOL research showed that differences greater than 0.10–0.15 SD units are clinically significant. The magnitude of treatment differences in this study included 0.59 SD units for global symptom distress scale and 0.35 SD units for cognitive function and perceived health status. As the authors commented, these changes are similar in magnitude to those seen by patients undergoing successful hip arthoplasty. One possible explanation for the difference between this study and previous investigations may relate to the fact that the authors devised and used an instrument that was more diabetes-specific. In addition, the authors cite the low incidence of hypoglycemia in the intervention group and the substantial hyperglycemia in the control group as contributing to the demonstration of treatment benefits. One could argue that QOL measurements may be among the most important therapeutic outcomes since they focus on people's perceptions of their own physical and mental health and their ability to function in daily life. Moreover, in Dr. Testa's study, the QOL measures correlated strongly with employment activity. Thus, study patients receiving the active intervention had significantly less absenteeism and fewer bed days and restricted activity days. Applying Bureau of Census statistics to this data, the authors calculated substantial economic value associated with improved glycemic control in the study. Furthermore, active treatment was associated with diminished nonstudy-related health care utilization producing an estimated savings of $11 per patient per month. We believe the implications of these findings are quite profound. In recent years, there has been increasing concern about the cost of medical care. We suspect that many employers view their expenditures for health care as simply a cost of doing business, with the major benefit limited to the recruitment and retention of workers. Few chief executive officers probably see any way to relate their health care costs to worker productivity, and in recent years some employers have limited or even eliminated health care benefits for workers. The study by Dr. Testa and Dr. Simonson makes the point that improved health care can be associated with both enhanced worker productivity and decreased utilization of medical services. The authors have provided evidence that by improving the health of workers, appropriate medical care can make an immensely important contribution to the economy. This contribution should be more regularly measured and considered when making judgments about the costs and benefits of therapies. In actual fact, this study likely underestimates the impact of improved glycemic control since there was no measure of the relative productivity of workers in the two groups during their work activities. One might suspect that diabetic subjects with poor glycemic control would be less productive than those enjoying good blood glucose control. The benefits of improved QOL may far exceed any associated economic value for patients and their families. Indeed, it is hard to accurately place a dollar value on improvements in daily functioning at work or at home, as well as on cognitive function and physical and emotional well-being. We agree with the authors' contention that patients' health perceptions and QOL should be a focus when assessing the benefit of therapies. The potential savings should offset some of the cost of providing improved care. Moreover, future investigations that might demonstrate the QOL and economic value of effective therapies of chronic diseases such as diabetes would strengthen our efforts at advocacy for the health care resources needed by our patients. REFERENCES 1Testa MA, Simonson DC, Turner RR: Valuing quality of life and improvements in glycemic control in people with type 2 diabetes. Diabetes Care 21 (Suppl 3):C344-52, 1998. 2Testa MA, Nackley JF: Methods for quality-of-life studies. Ann Rev Public Health 15:535-39, 1994. 3Weinberger M, Kirkman MS, Samsa GP, Cowper PA, Shortliffe EA, Simel DL, Feussner JR: The relationship between glycemic control and health-related quality of life in patients with non-insulin-dependent diabetes mellitus. Med Care 32:1173-81, 1994. Lawrence Blonde, MD, is head of the Section of Endocrinology, Diabetes, and Metabolic Diseases and vice chair of the Department of Medicine at the Ochsner Clinic and Alton Ochsner Medical Foundation in New Orleans, La. Jayant Dey, MD, is a Fellow in the Endocrinology and Metabolic Diseases Training Program at the Alton Ochsner Medical Foundation. Copyright © 1999 American Diabetes
Association For Technical Issues contact webmaster@diabetes.org |