Original Article

Predictors of Adherence to Type 2 Diabetes Medication

Citation: Pirdehghan A, Poortalebi N. Predictors of Adherence to Type2 Diabetes Medication. J Res Health Sci. 2016; 16(2):72-75.

Introduction

Diabetes is one of the most increasing common public health issues globally. This disease known to be the fifth cause of mortality in the western societies ¹ and fourth reason of referring to the physicians, has been allocated 15% of health care costs in the USA ² .

The incidence rate of diabetes type 2 is increasing in the world which can be due to life style change resulting in obesity and reduction of physical activity. The incidence of diabetes in Iran is accounted for 14% in the population over 30 ³ . Training diabetic patients along with adherence allows the patients to take more responsibility to care themselves ⁴ . Adherence is the amount of acceptance and adaptability with caregivers’ advice ⁵ . According to WHO, adherence includes the change in individual`s behavior, drug administration, regiment follow-up, life style change and application of caregivers’ advice ⁶ . For 36%-93% of cases, medication adherence by diabetic type 2 patients is not satisfactory ⁷ . There have been some discussions about the effects of weak adherence such as weak control of blood sugar and preventable hospitalization in chronic diseases such as diabetes and blood pressure ^8-10 .

Different studies have mentioned several factors low of medication adherence such as the number of administered medications, complexity of treatment regiment, comorbidity, weak family support and inaccessibility to medication or lack of insurance coverage for the required drugs ^6,11-13 .

Regarding the importance of adherence in management of diabetic patients, we aimed to determine the factors influencing the medication adherence and dietary regiment in type 2 diabetic patients so that there can be suggested some strategies to plan interventions.

Methods

This cross sectional was study in non-randomized sampling method conducted on 300 type2 diabetic patients referred for control and complication follow up. After Institutional Review Board approval, study participants were recruited from General Internal Medicine Clinic, Yazd Shohdaye Kargar Hospital, Yazd City between September and December 2013. Trained staff identified patients using a list of adults with diabetes coming in for visits each day and approached these potential participants in the waiting room. All 30- yr- old or older patients reporting a history of type 2 diabetes for at least 12 months prescribed diabetes medication were enrolled. Exclusion criteria included patient who refused insulin therapy recommendation and stayed on drugs for different reasons.

Each consented participant was interviewed by a trained study member using a questionnaire in three sections: Socio-demographic questions, self-reported Morisky medication adherence scale and Disease and medication beliefs Patient’s questionnaire.

Socio-demographic factors, diabetes history, and co morbidities (medical and psychiatric) were self-reported. The primary outcome measure of adherence to diabetes medicines was determined using a modified version of the six items, self-reported Morisky medication adherence scale ¹⁴ . Each item is in a yes/no format with possible score of four to six, equating good adherence and zero to three typically considered as poor adherence. The Morisky scale has been used across many chronic diseases, including diabetes, as a self-reported measure of adherence to medications and has demonstrated good reliability and predictive validity ^15-17 . In present study, it had proper reliability (Cronbach alpha: necessity=0.70).

Disease and medication beliefs Patient's disease beliefs were measured with 19 item assessing beliefs about the chronicity, cause, consequences and controllability of their diabetes using the Brief-Illness Perception Questionnaire (test–retest reliability across domains (0.42 to 0.72) as a framework ¹⁸ .

Medication beliefs were assessed using the five items of greatest relevance to diabetes medication adapted from the Beliefs about Medicines Questionnaire (Cronbach alpha: necessity=0.74, concerns=0.80) ¹⁹ .

Additional questions assessed familial support and access to medicine in tree scale (poor, moderate and good) and tendency to eat fruits vegetables, meat and sweetmeat in score rang 1 to 10.

Categorical variables are reported as percentages and continuous variables as means. Socio-demographics, medical history, beliefs and knowledge rates were calculated using descriptive statistics. The final multivariable logistic regression model was developed to identify independent predictors of poor adherence based on the variables associated with adherence in the univariate analysis using a Forward conditional model. All statistical analyses were performed using SPSS.19 statistical software (Chicago, IL, USA). P<0.05 was considered statistically significant.

Results

The 300 study subjects were all clinic attending patients with type 2 diabetes of age between 30 and 85 yr. More than 50% of participants had longstanding diabetes (7 yr and more) and more participants were on medications included in glibenclamide or metformin.

Respondents reported high levels of co morbid conditions (hypertension 189 (63%) and hyperlipidemia 171 (57%)) commonly associated with diabetes (Table1). Totally, 101 (33.7%) of patients reported poor adherence with their diabetes medication.

Among demographic and clinical variables analyzed, being single or divorced, drug medication versus insulin therapy, younger age and lower duration of disease had a significant relationship with poor adherence in diabetic patients (P<0.05) (Table 1 and 2).

Across some social factors, poor familial support, family disease related advises and insufficient accessibility to medications were significant related agents with poor adherence (P<0.05) (Table 2).

Based on the results of simple logistic regression, significantly related risk variables for "poor adherence", were candidate as to enter in the multivariate analysis model. Among them poor familial support and tendency to consume sweets were considered as predicting and belief about medication and tendency to consume vegetables as protective factors (Table 3).

Discussion

66.3% of patients had acceptable medication adherence. These were varied in other studies. For example, in Malaysia, aiming to investigate the medication adherence and the factors related to non-adherence to treatment on 557 type 2 diabetic patients, 53% of patients had unfavorable medication adherence ²⁰ . In another study in France, aiming to evaluate self-reporting medication adherence and factors related to weak medication adherence on type 2 diabetic patients, 12% of patients had weak medication adherence, 49% medium and 39% had good adherence ²¹ .

The difference of results in studies can be related to the design of studies, demographic differences of the subjects, different methods in investigating medication adherence and different situation of training patients. In our study, the frequency of patients under study along with unfavorable medication adherence was underestimated due to the following reasons: First, the determination of medication adherence was based on asking the patients, therefore, some patients might answer the questions in favor of the interviewer making the medication adherence unreal. Second, the probability of volunteer bias must have been considered in our study. Surely, those who regularly refer to control blood sugar and visit the physician in health centers have better medication adherence at home and apply the physicians` advice. Some others who are not included in our study due to non-referral to health centers had less medication adherence.

In this study, there was a significant difference between the time of diabetes diagnosis and age with medication adherence in that age group over 75 yr showed higher adherence than other groups. In a study in Tehran, on type 2 diabetic patients for their medication adherence in the last month and their awareness of diabetes, symptoms and attitude on the necessity of medication, subjects over 45 yr showed higher medication adherence ²² .

Some studies have regarded the medication adherence in patients over 75 yr due to the memory disorder and movement, visual and depression disorder lower than the younger ones inconsistent with our study ²³ . The significant relationship between age and medication adherence in our study is due to the fact that the elderly see themselves more vulnerable to death, dependency on the family and the symptoms of disability.

In this study, there was a significant relationship between marital status and medication adherence so that the married subjects showed greater adherence than two other groups, as consistent with another study ²⁴ .

In present study, there was a significant relationship between medication adherence with marital status, family support and access to drug in that medication adherence in subjects with good family support and access to drug was remarkably greater. In another study, factors related to weak medication adherence in patients over 45 yr were lack of family support and weak access to drug ²¹ . In England, non-supportive behaviors of family were related to weak diabetic medication adherence and reduced lowering blood sugar ²⁵ .

Our results showed that in subjects believing the disease and stronger treatment, the medication adherence was greater. False belief was the barrier in control and behavior management and consequently the weak medication adherence of patients ²⁶ .

In this study, there was a significant relationship between medication adherence and dietary regiment with patient’s efficaciosity to family members’ advice to suitable regiment in that they had more adherence. In Botswana, lack of admission of advice related food regiment and sports led to non-admission of food regiment and disease exacerbation, as consistent with the present study ²⁷ .

Our results should be viewed with consideration of limitations. While our study population was only the patients who referred to general internal medicine clinic in order to follow the complications of their disease, the generalizability of our observations to other settings is unknown, and should be explored in future work. And maybe in our research more number of sample sizes could detect weaker associations.

Conclusions

More than 30% of diabetic patients had unacceptable adherence. In multivariate analyses, poor familial support, and tendency to consume sweets were considered as predicting and belief about medication and tendency to consume vegetables as protective factors. Maybe the mention above could be considered as logical goals for educational interventions to modify diabetes self-management in future programs.

Acknowledgments

We gratefully acknowledge all health professionals staff in Yazd Shohdaye Kargar Hospital General Internal Medicine Clinic that helped for data collection.

Conflict of interest statement

The authors declare that have no conflict of interests.

Highlights

References

1. Beulens JW, Grobbee DE, Nealb B. The global burden of diabetes and its complications: an emerging pandemic. Eur J Cardiovasc Prev Rehabil 2010; 17(1 suppl):S3-S8. [ Google Scholar]
2. Andersen R, Newman JF. Societal and individual determinants of medical care utilization in the United States. Milbank Q 2005; 83(4):1-28. [ Google Scholar]
3. Baghianimoghadam M, Afkhami Ardekani M. The effect of educational intervention on quality of life of diabetic patients type 2, referee to diabetic research centre of Yazd. Health Horiz 2008; 13(4):21-28. [ Google Scholar]
4. Kahn SE, Haffner SM, Heise MA, Herman WH, Holman RR, Jones NP. Glycemic durability of rosiglitazone, metformin, or glyburide monotherapy. N Engl J Med 2006; 355(23):2427-2443. [ Google Scholar]
5. Mulvaney SA, Hood KK, Schlundt DG, Osborn CY, Johnson KB, Rothman RL. Development and initial validation of the barriers to diabetes adherence measure for adolescents. Diabetes Res Clin Pract 2011; 94(1):77-83. [ Google Scholar]
6. Cramer JA. A systematic review of adherence with medications for diabetes. Diabetes Care 2004; 27(5):1218-1224. [ Google Scholar]
7. Grant RW, Devita NG, Singer DE, Meigs JB. Polypharmacy and medication adherence in patients with type 2 diabetes. Diabetes Care 2003; 26(5):1408-1412. [ Google Scholar]
8. Rozenfeld Y, Hunt JS, Plauschinat C, Wong KS. Oral antidiabetic medication adherence and glycemic control in managed care. Am J Manag Care 2008; 14(2):71-75. [ Google Scholar]
9. Ahmadipour H, Farajzadegan Z, Kachoei A, Pirdehghan A. Secondary prevention by enhancing adherence in diabetic patients. Int J Prev Med 2010; 1(1):50-55. [ Google Scholar]
10. Jung O, Gechter JL, Wunder C, Paulke A, Bartel C, Geiger H. Resistant hypertension? Assessment of adherence by toxicological urine analysis. J Hypertens 2013; 31(4):766-774. [ Google Scholar]
11. Stopford R, Winkley K, Ismail K. Social support and glycemic control in type 2 diabetes: a systematic review of observational studies. Patient Educ Couns 2013; 93(3):549-558. [ Google Scholar]
12. Dunkley AJ, Bodicoat DH, Greaves CJ, Russell C, Yates T, Davies MJ. Diabetes prevention in the real world: effectiveness of pragmatic lifestyle interventions for the prevention of type 2 diabetes and of the impact of adherence to guideline recommendations a systematic review and meta-analysis. Diabetes Care 2014; 37(4):922-933. [ Google Scholar]
13. Krass I, Schieback P, Dhippayom T. Adherence to diabetes medication: a systematic review. Diabet Med 2015; 32(6):725-737. [ Google Scholar]
14. Morisky DE, Green LW, Levine DM. Concurrent and predictive validity of a self-reported measure of medication adherence. Med Care 1986; 24(1):67-74. [ Google Scholar]
15. Krapek K, King K, Warren SS, George KG, Caputo DA, Mihelich K. Medication adherence and associated hemoglobin A1c in type 2 diabetes. Ann Pharmacother 2004; 38(9):1357-1362. [ Google Scholar]
16. Al-Qazaz HK, Hassali MA, Shafie AA, Sulaiman SA, Sundram S, Morisky DE. The eight-item Morisky Medication Adherence Scale MMAS: translation and validation of the Malaysian version. Diabetes Res Clin Pract 2010; 90(2):216-221. [ Google Scholar]
17. Morisky DE, Ang A, Krousel‐Wood M, Ward HJ. Predictive validity of a medication adherence measure in an outpatient setting. J Clin Hypertens 2008; 10(5):348-354. [ Google Scholar]
18. Broadbent E, Petrie KJ, Main J, Weinman J. The brief illness perception questionnaire. J Psychosom Res 2006; 60(6):631-637. [ Google Scholar]
19. Horne R, Weinman J, Hankins M. The beliefs about medicines questionnaire: the development and evaluation of a new method for assessing the cognitive representation of medication. Psychol Health 1999; 14(1):1-24. [ Google Scholar]
20. Ahmad NS, Ramli A, Islahudin F, Paraidathathu T. Medication adherence in patients with type 2 diabetes mellitus treated at primary health clinics in Malaysia. Patient Prefer Adherence 2013; 7:525-530. [ Google Scholar]
21. Tiv M, Viel J-F, Mauny F, Eschwege E, Weill A, Fournier C. Medication adherence in type 2 diabetes: the ENTRED study 2007, a French population-based study. PLoS One 2012; 7(3):e32412. [ Google Scholar]
22. Fataneh Dabaghian, Sedigheh Soheilikhah, Karbakhsh M. medication adherence in patient with type 2 diabetes admited to Shariati and Imam Khomeini hospital. Payesh Quarterly 2006; 4(2):103-111. [ Google Scholar]
23. Commission P. Potential Benefits of the National Reform Agenda. SSRN Working Paper Series. 2007.
24. Durán-Varela BR, Rivera-Chavira B, Franco-Gallegos E. Pharmacological therapy compliance in diabetes. Salud Publica Mex 2001; 43(3):233-236. [ Google Scholar]
25. Mayberry LS, Osborn CY. Family support, medication adherence, and glycemic control among adults with type 2 diabetes. Diabetes Care 2012; 35(6):1239-1245. [ Google Scholar]
26. Mann DM, Ponieman D, Leventhal H, Halm EA. Predictors of adherence to diabetes medications: the role of disease and medication beliefs. J Behav Med 2009; 32(3):278-284. [ Google Scholar]
27. Ganiyu AB, Mabuza LH, Malete NH, Govender I, Ogunbanjo GA. Non-adherence to diet and exercise recommendations amongst patients with type 2 diabetes mellitus attending Extension II Clinic in Botswana. Afr J Prim Health Care Fam Med 2013; 5(1):1-6. [ Google Scholar]