Factors Affecting Use of Insulin Pens by Patients with Type 2 Diabetes

Transcription

1 Diabetes Care Publish Ahead of Print, published online November 26, 2007 Factors Affecting Use of Insulin Pens by Patients with Type 2 Diabetes Richard R. Rubin, PhD 1,2 Mark Peyrot, PhD 1,3 1= Department of Medicine, Johns Hopkins University School of Medicine; 2 = Department of Pediatrics, Johns Hopkins University School of Medicine; 3 = Department of Sociology, Loyola College in Maryland Corresponding Author: Richard R. Rubin, PhD 946 E. Piney Hill Road Monkton, MD rrubin4@jhmi.edu Received for publication 2 October 2007 and accepted in revised form 14 November Copyright American Diabetes Association, Inc., 2007

2 ABSTRACT Objective: To assess factors that might affect patient use of insulin pens. Methods: Patients (N= 600, 300 using vial and syringe, 300 using pen) were recruited from national panels to participate in computer-assisted telephone interviews. Measures included: demographic characteristics; diabetes treatment and self-care factors; perceptions of pen convenience, clinical efficacy, facilitation of self-care, and cost; and degree of physicians recommending pen use. Results: Physician recommendation of pen use powerfully discriminated pen users from nonusers (OR=135.6). Other factors that discriminated pen users included physicians presenting pens as an option (OR=14.1), and patient perceptions that pens facilitate diabetes self-care (OR=20.2) and are not costly (OR=4.8). Conclusions: The physician s role in presenting the pen as an option and recommending pen use was a critical factor in patient pen use. Enhanced physician education regarding the potential benefits of pen use, and encouraging physicians to discuss pen use with patients could improve diabetes outcomes. 2

3 D espite the potential of alternative insulin delivery systems such as pens for improving patient treatment satisfaction (1-6), treatment adherence (6), and clinical outcomes (2, 6-7), use of these systems in the U.S. is limited. Among the approximately 4.7 million people who use insulin in the U.S., fewer than 20% use insulin pens (8). More wide-spread pen use in the U.S. could lead to improved treatment satisfaction and adherence, and to better clinical outcomes, but little is known about factors that affect patients use of insulin pens. The current paper was designed to clarify the factors associated with patient use of insulin pens. RESEARCH DESIGN AND METHODS Data were obtained through computerassisted telephone interviews (CATI) of panels from a national sample of persons in the US self-identified as having diabetes. Sampling and data collection was performed by GFK, a contract research organization. An institutional review board approved this study. Potential respondents were contacted by telephone and asked to participate in a survey about diabetes. Inclusion criteria for participants in the current study were: 1) selfreported diagnosis of diabetes by a physician (>1 year before survey); 2) age > 35 years (thus almost all participants had type 2 diabetes); 3) taking insulin > 1 year; 4) had heard of insulin pens. Patients who had ever used an insulin pump were excluded, as were those who had participated in diabetes-related research in the previous 3 months. The responses of 600 patients are reported here, including 300 who were taking insulin using a vial and syringe, and 300 who were using a pen. Data collected from participants (all variables appear in Table 1) included: (1) basic demographic information; (2) disease characteristics; (3) medical insurance coverage for pens; (4) whether pen use was encouraged by the patient s physician, discouraged by the physician, discussed as an option, or not discussed at all and; (5) participants perceptions of how pen use compared with vial and syringe use (six-point scale with pen much better = higher score, pen much worse = lower score) in terms of clinical effectiveness (controlling blood glucose levels), convenience, cost, and facilitation of self-care (making it easier to adhere to the diabetes self-care regimen). Patient questionnaires were constructed on the basis of focus groups conducted with patients and physicians. Hierarchical stepwise logistic regression was used to identify factors which independently discriminated between those who were currently using a pen and those who had never used a pen. RESULTS Table 1 shows the results of logistic regression analyses conducted to discriminate those who used a pen (scored 1) from those who did not (scored 0). The first analysis (column 2, labeled step 1) forced into the model a number of control variables. The second analysis (column 3, labeled step 2) added as independent variables physician action measures that met the forward stepwise criterion (p<.05): whether the physician encouraged pen use and whether the physician mentioned pen use as an option. The third analysis (column 4, labeled step 3) added as independent variables measures of patients pen perception that met the forward stepwise criterion (p<.05): respondents perceptions of higher pen effectiveness in improving self-care and lower pen cost. Variables that did not meet the forward stepwise criterion (i.e., perceptions of pen clinical effectiveness and convenience) were not entered in the latter analysis. 3

4 Physician recommendation of pen use powerfully discriminated pen users from nonusers (OR=135.6). Other factors that discriminated pen users included physicians presenting pens as an option (OR=14.1), and patient perceptions that pens facilitate diabetes self-care (OR=20.2) and are not costly (OR=4.8). CONCLUSIONS Patients with type 2 diabetes do not depend on exogenous insulin for survival, but over time most of these individuals will require supplemental insulin, as a consequence of decreased endogenous insulin production (9-10). Yet many patients with type 2 diabetes do not initiate insulin therapy as soon as they should (11-13). Alternative insulin delivery systems such as pens could lower some barriers to initiating insulin therapy, but little is known about factors associated with patients use of pens. This study considers these issues in a national panel sample of adults with type 2 diabetes who were taking insulin and had heard of pens. Physicians presentation of insulin pens was the most powerful predictor of pen use. Merely presenting the pen as an option was associated with a substantial increase in pen use, and encouragement of pen use was associated with a 100 times greater likelihood of pen use compared to respondents whose physicians did not discuss pen use or who discouraged pen use. This finding, while not unexpected, demonstrates the importance of the physician s role in patient decisionmaking (14). Patients perceptions of insulin pens were also an important predictor of pen use. The perception that ease of pen use facilitates diabetes self-care also strongly discriminated pen users from vial and syringe users. While this belief is closely related to convenience, our findings highlight the fact that it is not convenience per se that is important, but the degree to which ease of use facilitates selfcare. Future research should distinguish between these closely related concepts, to avoid missing a potential key advantage of insulin pens, dismissing it as a matter of mere convenience. Perception of pen cost also discriminated pen users from non-users; in the present study cost was the most common reason participants gave for not using a pen, with 23% of participants citing this reason. The design of this study is cross-sectional, so we cannot determine the temporal ordering of the associations we report. In particular, the association between pen use and the perception that pen use facilitates diabetes self-care could reflect the fact that study participants chose to use pens because they believed these devices would facilitate diabetes regimen adherence. Alternatively, pen users may have become aware of this advantage only after they began using these devices. In either case, the implications of this association are meaningful. The fact that physician recommendation of pen use, or even discussing insulin pens as an option, has enormous impact on a patient s choice of insulin delivery systems has two important implications. First is the need to increase physician awareness of the potential benefits of pen use, including improved treatment satisfaction (1-6), treatment adherence (6), and clinical outcomes (2, 6-7). Second, this finding suggests that physicians should talk to their patients about pen use to insure that patients are aware of this potentially beneficial insulin delivery option. The other major implication of this study is that physicians, patients, and payors should recognize that making it easier for patients to take better care of their diabetes is not a trivial benefit. Burden of treatment is a significant barrier to improved self-care, and reducing this barrier could make an important contribution to improved diabetes outcomes. Acknowledgements: This study was funded by an unrestricted grant from Novo Nordisk to the authors. 4

5 REFERENCES 1. Rubin RR, Peyrot M: Quality of life, treatment satisfaction, and treatment preference associated with use of a pen device delivering a premixed 70/30 insulin aspart suspension (aspart protamine suspension/soluble aspart) versus alternative treatment strategies. Diabetes Care 27: , Shelmet J, Schwartz S, Cappleman J, Paterson G, Skovlund S, Lyness W, Liang J, Lytzen L, Nicklasson L for the Innolet Study Group: Preference and resource utilization in elderly patients: Innolet vs. vial/syringe. Diabetes Research and Clinical Practice 1:27-35, Stocki K, Ory C, Vanderplas A, Nickalsson L, Lyness W, Cobden D, Chang E: An evaluation of patient preference for an alternative insulin delivery system compared to standard vial and syringe. Curr Med Res Opin 23: , Summers KH, Szeinbach SL, Lenox SM: Preference for insulin delivery systems among current insulin users and nonusers. Clin Ther 9: , Kortykowski M, Bell D, Jacobsen C, Suwannasari R, Flexpen Study Team: A multicenter, randomized, open-label, comparative, two-period crossover trial of preference, efficacy, and safety profiles of a prefilled, disposable pen and conventional vial/syringe for insulin injections in patients with type 1 or 2 diabetes mellitus. Clin Ther 11: , Lee WC, Balu S, Cobden D, Joshi AV, Pashos CL: Medication adherence and associated health-economic impact among patients with type 2 diabetes mellitus converting to insulin pen therapy: an analysis of third-party managed claims data. Clin Ther 28: , Pawaskar MD, Camacho FT, Anderson RT, Cobden D, Joshi AV, Balkrishnan R: Health care costs and medication adherence associated with initiation of insulin pen therapy in Medicaid-enrolled patients with type 2 diabetes: a retrospective database analysis. Clinical Therapeutics 29: , GFK Market Measures: 2006 Roper Survey of U.S. Diabetes Patient Market 9. De Witt DE, Hirsch IB: Outpatient insulin therapy in type 1 and type 2 diabetes mellitus: a scientific review. JAMA 289: , Turner RC, Cull CA, Frighi V, Holman RR, for the UKPDS Group: Glycemic control with diet, sulfonylureas, metformin, or insulin in patients with type 2 diabetes mellitus: Progressive requirements for multiple therapies. (UKPDS 49). JAMA 281: , Riddle MC: The underuse of insulin therapy in North America. Diabet Metab Res Rvw 28: , Davidson MB: Early insulin therapy for type 2 diabetes. Diabetes Care 28: , Polonsky WH, Fisher L, Guzman S, Villa-Caballero L, Edelman SV: Psychological insulin resistance in patients with type 2 diabetes: The scope of the problem. Diabetes Care 28: , Rubin RR, Peyrot M, Siminerio LM, on behalf of the International DAWN Advisory Panel: Health care and patient-reported outcomes: Results of the cross-national Diabetes Attitudes, Wishes, and Needs (DAWN) Study. Diabetes Care 29: ,

6 TABLE 1. Logistic Regression Analysis of Insulin Pen Use OR (step 1) OR (step 2) OR (step 3) Age (years) Race (white) Some college # College degree # Working * 2.53* Disabled Hand problems Vision problems Travel frequency $ Meals out frequency * 1.29 Medicare coverage & Medicaid coverage & 1.89* 2.50* 1.80 Private insurance & 1.95** Other insurance & See PCP for diabetes See diabetes specialist 1.65* Duration diabetes (years) Duration insulin (years).94*.94*.94 SMBG frequency 1.82*** 2.17** 2.16* MD says pen an 14.38*** 14.09*** MD encourages pen *** *** Pen facilitates self-care 20.15*** Pen cost 4.79* Nagelkerke R-square.19***.71***.74*** * p <.05; ** p <.01; *** p <.001 Note: all variables have 0-1 scoring except as noted $: scoring = 1-4, with 1 = never, 2 = rarely, 3 = few times a year, 4 = monthly, 5 = weekly +: scoring = 1-6, with 1 = never, 2 = rarely, 3 = few times a year, 4 = few times a month, 5 = few times a week, 6 = daily #: reference is those with no college education &: reference is those without reference is those whose physician did not discuss pen or discouraged pen use 6