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Original Research

Medication-related risk factors associated with health-related quality of life among community-dwelling elderly in China

, , , &
Pages 529-537 | Published online: 10 Apr 2018

Abstract

Background

Previous studies have demonstrated that medication adherence has an impact on health-related quality of life (HRQoL). However, other medication-related factors that may influence HRQoL have not been extensively studied, especially factors based on the Medication-Risk Questionnaire (MRQ), and such studies are mostly done in Western countries. Our objective was to explore risk factors associated with HRQoL among community-dwelling elderly with chronic diseases in mainland China, especially the medication-related risk factors regarding MRQ.

Methods

The study was conducted in a community health service center through surveys to eligible patients. The main outcomes of HRQoL were assessed by the EuroQol-5D (EQ-5D) scale and EQ-visual analog scale (EQ-VAS). Medication-related risk factors according to MRQ associated with HRQoL were identified using a multiple linear regression.

Results

A total of 311 patients were analyzed, averaging 71.19±5.33 years, and 68.8% were female. The mean EQ-5D index was 0.72±0.09, and the mean EQ-VAS score was 71.37±11.97. The most prevalent problem was pain/discomfort, and 90.0% believed that they could take care of themselves without any problems. Sex, age, educational level, frailty, function status, and certain medication-related factors regarding MRQ were found to be significant factors impacting the HRQoL. A multivariate analysis showed that MRQ factors of polypharmacy, multimorbidity, feeling difficultly with taking medicines as prescribed, and taking medicines with narrow therapeutic index had negative impacts on the quality of life.

Conclusion

Patient’s internal characteristics and medication-related risk factors according to MRQ were associated with quality of life. The results of the MRQ is an indicator of quality of life that can identify patients who need interventions.

Introduction

The population around the world is rapidly aging,Citation1,Citation2 and the elderly population, aged ≥60 years, is expected to grow by 56% from 2015 to 2030, with the fastest growth in developing countries – India (64%), South Korea (77%), and China (71%).Citation3,Citation4 However, living longer does not necessarily mean health and longevity,Citation2 and a person’s quality of life may decline. With aging, an elderly may frequently suffer from multimorbidity and experience symptoms due to age-related changes in pharmacokinetics and pharmacodynamics.Citation5,Citation6 The World Health Organization (WHO) report on Aging and Health defines “healthy aging” as the process of developing and maintaining the functional ability that enables well-being in older age, a process that runs through a person’s entire life rather than a specific point in time.Citation1,Citation4

Health-related quality of life (HRQoL) is an important indicator of an individual’s health status, which can be used to evaluate the effectiveness of health care interventions and improve treatment outcomes.Citation7,Citation8 HRQoL is a multidimensional concept, which is defined as the state of health of individuals under the influence of illness, medical interventions, aging, and social changes, as well as subjective satisfaction associated with their economic, social, and cultural values.Citation9Citation11 HRQoL measures have been identified as a significant endpoint for understanding the health status of older people and evaluating the effects of other related factors for the quality of life.Citation12

Medications are widely used in the elderly to reduce morbidity and mortality, and they have an important role in older patients’ health status.Citation13 However, medications may also increase the risk of medication-related problems (MRPs), which result in additional health care costs, and the associated negative health outcomes have attracted a widespread attention. Many studies identified the relationship between medications and quality of life, which demonstrated the effects of medication adherence on HRQoL.Citation14Citation16 However, other medication-related factors that may influence HRQoL have not been extensively studied, especially factors based on medication-risk questionnaire (MRQ). The MRQ is a validated self-administered toolCitation6,Citation17,Citation18 that can identify patients who are at a higher risk of experiencing an MRP, notably for the elderly. A better understanding of the relationship between medication-related factors and HRQoL could assist in improving the quality of life in the elderly. This study aimed to explore the relationship between medication-related factors and HRQoL in community-dwelling elderly patients with chronic diseases in mainland China.

Methods

Setting and participants

The study took place in a Community Health Service Center (CHSC) in the suburb of Chongqing, a national central city located in the southwest of China, from March 1 to May 31, 2016. The study subjects were patients who came to the CHSC for routine physical examinations. Patients were invited to participate in the study if they met the following criteria: 1) age ≥65 years and 2) taking one or more chronic medications for a period of ≥3 months. Exclusion criteria were patients with 1) severe or terminal illness, 2) functional or cognitive severe impairment (Barthel index ≤60 or a score of <10 in HDS-R), and 3) inability to complete questionnaires.

A sample size of 196 was calculated based on a prevalence of chronic diseases at 85%,Citation19 with a precision of 5% and a confidence interval of 95%. We invited 350 patients to participate in the study, 15 patients refused (4.3%), and 24 patients were excluded for the following reasons: severe cognitive impairment (n=5), severe functional impairment (n=7), and incomplete information (n=12). Finally, a total of 311 patients participated and were included in the final analysis.

Survey instruments and data collection

Demographic information was obtained for the patient sample on sex, age, education level, residence setting, marital status, and type of health insurance. Clinical information collected was chronic disease states and chronic medications. Each patient was also assessed on cognitive function using the Revised Hasegawa Dementia Scale (HDS-R), function status using the basic activities of daily living (BADL), frailty using the Reported Edmonton Frail Scale (REFS), medication-related risk factors using the MRQ, and HRQoL using the EuroQol-5D (EQ-5D) scale. The total score of the REFS ranges between 1 and 18, and a cutoff point for frailty is 8.Citation20 The HDS-R has a total score of 32.5, and a score of <10 is used to detect severe cognitive impairment.Citation21,Citation22 The BADL (Barthel index) is a 10-item scale, and the total score ranges from 0 to 100, with a score of ≤60 indicating functional impairments.Citation23 MRQ, first developed and validated by Barenholtz Levy in 2003,Citation18 has 10 items based on patient’s medication use, and each item has a “yes” or “no” option. EQ-5D scale, a well-known and widely used generic HRQoL instrument, was developed by the EuroQoL group.Citation24Citation26 EQ-5D has been used to evaluate the quality of life in Chinese.Citation27 The EQ-5D consists of the following two parts: the EQ-5D descriptive system and a EQ-visual analog scale (EQ-VAS). The EQ-5D descriptive system has five dimensions, including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression.Citation24,Citation26 Each dimension has the following three levels: no problems, some or moderate problems, and severe or extreme problems. The EQ-5D health states were converted into “the EQ-5D index”, a single index “utility” score, by using a scoring algorithm based on the overall population, and the EQ-5D index in this study was calculated by using the Japanese value set scoring algorithm as a Chinese scoring algorithm is not yet available.Citation28 The EQ-VAS is a 20 cm vertical VAS, with the top 100 points labeled “the best health status in mind” and the bottom 0 point labeled “the worst health status in mind”, and requires participants to rate their overall health on the vertical line that represents “your health status today”.

Four trained pharmacy students who were familiar with the study objectives and methodology conducted the surveys through face-to-face interviews. Surveys were first piloted in 20 patients to evaluate the validity and reliability of the questionnaires, and 18 (90.0%) patients completed. Final questionnaires in the study were appropriately adjusted based on the pilot study.

Statistical analysis

All statistical analyses were carried out by SPSS, version 22.0. A descriptive analysis was conducted for demographics, clinical characteristics, MRQ, and quality of life. Categorical variables were presented as frequencies and percentages, and continuous variables were presented as mean and standard deviation. The Student’s t-test was used for continuous variables, and chi-square test was used for categorical variables. A one-way analysis was performed to identify the relationships between factors and quality of life in both EQ-5D index and EQ-VAS. Medication-related risk factors according to MRQ were entered into a multiple linear regression model to further identify the association between medication-related risk factors and HRQoL. P<0.05 was considered as statistically significant. To prevent multicollinearity, a variance inflation factor (VIF) was generated among the variables. Multicollinearity is unlikely to be problematic if VIF <10.0.Citation29

Ethical approval

The study was approved by the Ethics Committee of The First Affiliated Hospital of Chongqing Medical University, and all participants signed informed consent forms.

Results

Participant characteristics

A total of 311 patients participated in the study, average age 71.19±5.33 years, and 68.8% were female. The characteristics and clinical data of the study population are summarized in . The mean number of chronic diseases was 4.47±2.10, and the three most common chronic conditions were hypertension (80.4%), hyperlipidemia (42.4%), and diabetes mellitus (37.6%). A total of 2.9% of patients were considered low function (dependent) and 10.3% were frail based on REFS. The daily average number of drugs taken was 4.96±2.50, and the three most common drug classes classified by the anatomical therapeutic chemical (ATC) classificationCitation30 were calcium channel blockers (66.6%), agents acting on the renin–angiotensin system (43.4%), and lipid-modifying agents (30.9%). In addition, 54.7% of patients were exposed to polypharmacy (taking ≥5 medications), 21.5% took Chinese herbal medicine, and 24.1% took dietary supplements.

Medication-risk questionnaire

According to the MRQ, a total of 89.4% of respondents reported having more than one risk factor for MRP. A significant number of patients took five or more different medicines (54.7%) or had high daily pill burdens (45.0%), taking ≥12 tablets or capsules. This may be related to 74.3% of patients having three or more medical problems. However, 85.2% of patients indicated that they know the reasons of taking their medications. The details are shown in .

Table 1 Frequencies of item responses to medication-risk questionnaire

The HRQoL

In total, the mean value of EQ-5D index was 0.72±0.09 and the mean EQ-VAS score was 71.37±11.97. The frequencies and percentages of each dimension are summarized in . Overall, the most prevalent problem was pain/discomfort, with 75.9% of the elderly rated as moderate and 3.2% rated as severe. The least frequent problem was the self-care dimension, and 90.0% of the elderly took care of themselves without any problems.

Table 2 Frequencies of each level to quality of life among participants

The percentages of individuals with problems in EQ-5D dimensions by age and sex are presented in . Women had statistically significantly higher percentages in pain/discomfort and anxiety problems than men. In addition, regarding age, there were significant differences in mobility and usual activities rated by patients.

Table 3 The percentage of participants with problems in EuroQol-5D index dimensions by age and sex

The related risk factors of quality of life

On the univariate analysis, the associations between the study variables, EQ-5D index, and EQ-VAS scores are shown in and . A significant difference in EQ-5D index was found between patients according to sex, age, the level of education, frailty, function status, and certain factors based on MRQ. Similarly, significant differences in EQ-VAS scores were found between patients according to sex, the level of education, residence, type of health insurance, frailty, and certain factors based on MRQ. Concerning factors according to MRQ, polypharmacy (Q1) was the most important factor related to lower scores in both EQ-5D and EQ-VAS ().

Table 4 Risk factors associated with EuroQol-5D (EQ-5D) index and EQ-visual analog scale (EQ-VAS) scores among participants

Table 5 Risk factors according to MRQ-associated EuroQol-5D (EQ-5D) index and EQ-visual analog scales (EQ-VAS) scores among participants

On the multivariate analysis, results of the multiple linear regression that aimed to recognize the relationship among MRQ, EQ-5D, and EQ-VAS are presented in . A lower quality of life was positively associated with polypharmacy (Q1), multimorbidity (Q5), feeling difficult to take medicines as prescribed (Q8), and using medicines with narrow therapeutic index (Q3).

Table 6 Multiple linear regression analyses between medication-related risk factors and variables related to EuroQol-5D (EQ-5D) index and EQ-visual analog scales (EQ-VAS) scores

Discussion

Our study investigated the quality of life in the community-dwelling elderly with chronic diseases in Chongqing, China, and we identified the risk factors associated with HRQoL, especially medication-related risk factors regarding MRQ. To the best of our knowledge, this is the first research exploring the relationship between MRQ and HRQoL in mainland China.

Overall, our mean score of EQ-VAS was similar to the study by Xu et al, who investigated the elderly older than 60 years in China.Citation31 However, compared with the finding reported by McCaffrey et al,Citation32 which measured the quality of life of adults in South Australian, our study had lower EQ-VAS scores, and this could be due to age differences in the study population.

Regarding the MRQ, a high prevalence of medication-related risk factors was found. Almost 9 of the 10 respondents reported having more than one medication-related risk factor in our findings, and this is consistent with the results from George et alCitation33 in a study of medication-related misadventure in the elderly, which reported that three-quarters of patients had one or more risk factors for MRP. Multimorbidity and polypharmacy had impacts on the high prevalence of risk factors present in our study sample. A vicious circle exists between multimorbidity and polypharmacy that the increase of chronic diseases results in an increased medication use and a decreased medication adherence, and in turn, polypharmacy increases the risk of adverse events and a decreased quality of life.Citation34Citation36

In terms of the EQ-5D dimensions, the most frequent problem was pain/discomfort, and, on the contrary, the self-care dimension was the least problem, which was consistent with the findings of other studies.Citation32,Citation37,Citation38 Moreover, the anxiety/depression dimension had a lower prevalence in our finding compared to other studies.Citation7,Citation37 This may indicate that our study patients have already accepted the mental reality, adapted to their internal physical characteristics, disease conditions, and adjusted to the external environment.

Similar to previous studies, our research demonstrated that there were significant differences of health status in terms of sex,Citation32,Citation39Citation41 women generally had lower scores in both EQ-VAS (69.79±10.93 vs 74.85±13.47) and EQ-5D index (0.71±0.08 vs 0.74±0.10) than men. Especially in terms of pain/discomfort (85.5% vs 64.9%) and anxiety dimensions (18.7% vs 5.2%), the prevalence of women experiencing these problems was higher than that of men. Also, our findings indicated that age had a negative effect on the quality of life, the EQ-5D index declined with age increase, and this highlights that aging has an impact on a person’s health status.Citation32,Citation39,Citation41

In our study, there were significant differences in quality of life according to sex, age, educational level, frailty, and function status, which were similar to previous studies.Citation32,Citation39 This means that patient’s intrinsic factors play a decisive role in quality of life. Most studies have shown that, besides patient intrinsic factors, medication-related factors may be determining factors in patient’s quality of life. Most of the reports about medication and quality of life are in the area of adherence. Iqbal et alCitation42 reported that adherence was a predictor among type 2 diabetes mellitus patients with an improved quality of life, and Adelufosi et alCitation43 found that medication nonadherence was related to worse quality of life in patients with schizophrenia. In our study, we also found that patients feeling difficult to take medicines as prescribed had a lower quality of life in the elderly, which is consistent with previous studies. The association between adherence and quality of life indicated that worse quality of life may be owing to patient attitudes to medications rather than medications themselves.Citation37

However, in many cases, it seems that other medication-related risk factors are strongly associated with a worse quality of life, especially risk factors according to MRQ.Citation6,Citation18 In our study, we found the following risk factors that were also associated with poor quality of life: taking five or more medicines, taking 12 or more tablets or capsules per day, taking medicines with narrow therapeutic index, and suffering from three or more comorbidities. These risk factors would help identify patients who need interventions desperately. We were unable to find any other similar studies that explore the relationship between MRQ and quality of life. However, studies that investigated the risk factors for health outcomes among patientsCitation33,Citation44,Citation45 have identified two risk factors of taking five or more medications, and taking medications with narrow therapeutic index increased the risk of adverse drug events and hospitalizations. Other studies on medication-related risk factors including a recent systemic review have reported that medication-related burden including multiple medicines, complex medication regimens, and the exchange of medication brands and instructions had negative influences on patients’ health beliefs and behaviors. This may contribute to a potential risk for the presence of drug-related problems and result in nonadherence and poorer outcomes.Citation46Citation49 These data strongly supported our findings that medication-related risk factors according to MRQ had a negative effect on the quality of life.

Our study is the first research to explore the relationship between medication-related risk factors based on MRQ and the quality of life among older patients in mainland China. The limitation of our study is the single-center survey; our findings may not be generalizable to the whole country. Since we only detected the medication-related risk factors affecting the quality of life, further research on the factors related to the quality of life is warranted.

Conclusion

Patient’s internal characteristics and medication-related risk factors according to MRQ are associated with quality of life. Polypharmacy, multimorbidity, poor medication adherence, and taking medicines with narrow therapeutic index have negative effects on quality of life. The results of the MRQ is an indicator of quality of life that can identify patients who need interventions. More research is needed on multidisciplinary interventions to reduce medication-related risk factors and improve the quality of life in the elderly.

Acknowledgments

SZ and LM should be considered co-first authors.

Supplementary material

Table S1 Demographic and clinical characteristics of participants

Disclosure

The authors report no conflicts of interest in this work.

References

  • BeardJROfficerAMCasselsAKThe World Report on Ageing and HealthGerontologist201656Suppl 2S163S16626994257
  • WHOWorld Report on Ageing and HealthGeneva, SwitzerlandWorld Health Organization2015
  • LimLMMcSteaMChungWWPrevalence, risk factors and health outcomes associated with polypharmacy among urban community-dwelling older adults in multi-ethnic MalaysiaPLoS One2017123e017346628273128
  • MerchantRAChenMZTanLWLLimMYHoHKvan DamRMSingapore healthy older people everyday (HOPE) study: prevalence of frailty and associated factors in older adultsJ Am Med Dir Assoc2017188734.e9734.e14
  • DelafuenteJCPharmacokinetic and pharmacodynamic alterations in the geriatric patientConsult Pharm200823432433418454589
  • LevyHBSteffenAMValidating the medication risk questionnaire with family caregivers of older adultsConsult Pharm201631632933727250075
  • MachonMLarranagaIDorronsoroMVrotsouKVergaraIHealth-related quality of life and associated factors in functionally independent older peopleBMC Geriatr20171711928088178
  • ChenHRosenzweigEBGotzkowskySKArnesonCNelsenACBourgeRCTreatment satisfaction is associated with improved quality of life in patients treated with inhaled treprostinil for pulmonary arterial hypertensionHealth Qual Life Outcomes2013113123496856
  • JarvelaJTKaasinenVPharmacotherapy and generic health-related quality of life in Parkinson’s diseaseActa Neurol Scand2016134320520926553754
  • ChenHTaichmanDBDoyleRLHealth-related quality of life and patient-reported outcomes in pulmonary arterial hypertensionProc Am Thorac Soc20085562363018625755
  • XuJZhangJFengLQiuJSelf-rated health of population in Southern China: association with socio-demographic characteristics measured with multiple-item self-rated health measurement scaleBMC Public Health20101039320598154
  • MunSParkKBaekYLeeSYooJHInterrelationships among common symptoms in the elderly and their effects on health-related quality of life: a cross-sectional study in rural KoreaHealth Qual Life Outcomes201614114627733204
  • LangfordBJJorgensonDKwanDPapoushekCImplementation of a self-administered questionnaire to identify patients at risk for medication-related problems in a family health centerPharmacotherapy200626226026816466331
  • Kastien-HilkaTRosenkranzBBennettBSinanovicESchwenkglenksMHow to evaluate health-related quality of life and its association with medication adherence in pulmonary tuberculosis – designing a prospective observational study in South AfricaFront Pharmacol2016712527303294
  • MarcumZAHanlonJTMurrayMDImproving medication adherence and health outcomes in older adults: an evidence-based review of randomized controlled trialsDrugs Aging201734319120128074410
  • SalehFMumuSJAraFHafezMAAliLNon-adherence to self-care practices & medication and health related quality of life among patients with type 2 diabetes: a cross-sectional studyBMC Public Health20141443124885315
  • MakowskyMJCaveAJSimpsonSHFeasibility of a self-administered survey to identify primary care patients at risk of medication-related problemsJ Multidiscip Healthc2014712312724591839
  • Barenholtz LevyHSelf-administered medication-risk questionnaire in an elderly populationAnn Pharmacother2003377–898298712841804
  • Tian ShibaoYMZhangHTianjing Ophthalmic HospitalThe system design of chronic disease managementChin Med Rec20141543
  • HilmerSNPereraVMitchellSThe assessment of frailty in older people in acute careAustralas J Ageing200928418218819951339
  • HashimotoHYamashiroMPostoperative delirium and abnormal behaviour related with preoperative quality of life in elderly patientsNihon Ronen Igakkai Zasshi19943186336387967149
  • WeiLICY-HXiao-GangYUObservation on therapeutic effect of acupuncture combined with medicine on mild cognition disorders in patients with post-strokeZhongguo Zhen Jiu20123215
  • QuinnTJLanghornePStottDJBarthel index for stroke trials: development, properties, and applicationStroke20114241146115121372310
  • RabinRde CharroFEQ-5D: a measure of health status from the EuroQol GroupAnn Med200133533734311491192
  • HollandRSmithRDHarveyISwiftLLenaghanEAssessing quality of life in the elderly: a direct comparison of the EQ-5D and AQoLHealth Econ200413879380515322991
  • DevlinNJBrooksREQ-5D and the EuroQol Group: past, present and futureAppl Health Econ Health Policy201715212713728194657
  • WangHKindigDAMullahyJVariation in Chinese population health related quality of life: results from a EuroQol study in Beijing, ChinaQual Life Res200514111913215789946
  • TsuchiyaAIkedaSIkegamiNEstimating an EQ-5D population value set: the case of JapanHealth Econ200211434135312007165
  • OstirGVEschbachKMarkidesKSGoodwinJSNeighbourhood composition and depressive symptoms among older Mexican AmericansJ Epidemiol Community Health2003571298799214652267
  • TayebatiSKNittariGMahdiSSIoannidisNSibilioFAmentaFIdentification of World Health Organisation ship’s medicine chest contents by Anatomical Therapeutic Chemical (ATC) classification codesInt Marit Health2017681394528357835
  • XuSTZhangJHZhengWGRelationship between quality of life and social support of the elderly in WeifangChin Med Ethics20173044
  • McCaffreyNKaambwaBCurrowDCRatcliffeJHealth-related quality of life measured using the EQ-5D-5L: South Australian population normsHealth Qual Life Outcomes201614113327644755
  • GeorgeJMunroKMcCaigDStewartDRisk factors for medication misadventure among residents in sheltered housing complexesBr J Clin Pharmacol200763217117617076694
  • VetranoDLBianchiniEOnderGPoor adherence to chronic obstructive pulmonary disease medications in primary care: role of age, disease burden and polypharmacyGeriatr Gerontol Int20171712
  • JaamMIbrahimMIMKheirNAwaisuAFactors associated with medication adherence among patients with diabetes in the Middle East and North Africa region: a systematic mixed studies reviewDiabetes Res Clin Pract201712911528499162
  • GencerMZAricaSUse of polypharmacy and herbal medication on quality of life in elderly patients at Okmeydani hospital’s polyclinics in Istanbul, TurkeyJ Pak Med Assoc201767689590028585589
  • Montiel-LuqueANunez-MontenegroAJMartin-AuriolesECanca-SanchezJCToro-ToroMCGonzalez-CorreaJAMedication-related factors associated with health-related quality of life in patients older than 65 years with polypharmacyPLoS One2017122e017132028166266
  • FangHFarooqUWangDYuFYounusMIGuoXReliability and validity of the EQ-5D-3L for Kashin-Beck disease in ChinaSpringerplus201651192427917330
  • Al-JabiSWZyoudSHSweilehWMRelationship of treatment satisfaction to health-related quality of life: findings from a cross-sectional survey among hypertensive patients in PalestineHealth Expect20151863336334825484002
  • RoalfeAKBryantTLDaviesMHA cross-sectional study of quality of life in an elderly population (75 years and over) with atrial fibrillation: secondary analysis of data from the Birmingham Atrial Fibrillation Treatment of the Aged StudyEuropace201214101420142722581625
  • Zamora-SanchezJJPerez-TortajadaGMendoza-Garcia de ParedesMDGuerrero-GancedoMMQuality of life perceived by complex patients in a case management program in primary health careEnferm Clin201222523924622902602
  • IqbalQUl HaqNBashirSBashaarMProfile and predictors of health related quality of life among type II diabetes mellitus patients in Quetta city, PakistanHealth Qual Life Outcomes201715114228709437
  • AdelufosiAOAdebowaleTOAbayomiOMosanyaJTMedication adherence and quality of life among Nigerian outpatients with schizophreniaGen Hosp Psychiatry2012341727922036736
  • LeeCYGeorgeJElliottRAStewartKPrevalence of medication-related risk factors among retirement village residents: a cross-sectional surveyAge Ageing201039558158720621929
  • SorensenLStokesJAPurdieDMWoodwardMRobertsMSMedication management at home: medication-related risk factors associated with poor health outcomesAge Ageing200534662663216267190
  • MohammedMAMolesRJChenTFMedication-related burden and patients’ lived experience with medicine: a systematic review and metasynthesis of qualitative studiesBMJ Open201662e010035
  • EtonDTRamalho de OliveiraDEggintonJSBuilding a measurement framework of burden of treatment in complex patients with chronic conditions: a qualitative studyPatient Relat Outcome Meas20123394923185121
  • HallNJRubinGPHunginAPDougallAMedication beliefs among patients with inflammatory bowel disease who report low quality of life: a qualitative studyBMC Gastroenterol200772017559670
  • WilliamsAFManiasEWalkerRAdherence to multiple, prescribed medications in diabetic kidney disease: a qualitative study of consumers’ and health professionals’ perspectivesInt J Nurs Stud200845121742175618701103
  • Barenholtz LevyHSelf-administered medication-risk questionnaire in an elderly populationAnn Pharmacother2003377–898298712841804