Skip to main content
SpringerLink
Log in

Validation of knowledge and adherence assessment tools among patients on warfarin therapy in a Saudi hospital anticoagulant clinic

  • Research Article
  • Published:
International Journal of Clinical Pharmacy Aims and scope Submit manuscript

Abstract

Background Although it can result in serious complications due to its narrow therapeutic index, warfarin is widely used in the treatment and prevention of thromboembolic disorders. However, patients’ adherence and knowledge are determinants of therapeutic success. Objective We sought to validate instruments to provide a reliable means of identifying gaps in patient understanding and nonadherence to inform targeted pharmacists’ interventions to improve these measures. Methods A cross-sectional survey was conducted. Patients’ knowledge about warfarin was rated using an Arabic-language tool. Medication adherence was assessed using the eight-item Morisky Medication Adherence Scale (MMAS-8). The international normalized ratio (INR) control was quantified by the Rosendaal Method. Setting At the Security Forces hospital anticoagulant clinic (ACC), Riyadh. Main outcome measure Validity of a Knowledge and adherence tool. Results Totally, 101 patients completed the questionnaires. Interestingly, the knowledge tool demonstrated good internal consistency (total Cronbach’s alpha = 0.75) and significant concurrent validity with adherence levels. Fifty-two patients were classified as having unsatisfactory knowledge. Deficiency in knowledge was most obvious with respect to the consequences of missing a dose and when to seek immediate medical attention. The MMAS-8 had moderate reliability (Cronbach’s alpha = 0.65); however, its concurrent validity with good INR control was not demonstrated. Conclusions This study revealed high prevalence of nonadherence and poor knowledge in the population visiting the ACC. Given that available knowledge and adherence tools seemed to have little validity in predicting clinical outcomes, structured tools should be designed, considering progression in clinical outcomes with future pharmacists’ interventions.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Larsen T, Skjøth F, Nielsen P, Kjældgaard J, Lip G. Comparative effectiveness and safety of non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation: propensity weighted nationwide cohort study. BMJ. 2016;353:i3189.

    Article  PubMed  PubMed Central  Google Scholar 

  2. Alquwaizani M, Buckley L, Adams C, Fanikos J. Anticoagulants: a review of the pharmacology, dosing, and complications. Curr Emerg Hosp Med Rep. 2013;1(2):83–97.

    Article  PubMed  PubMed Central  Google Scholar 

  3. Gurwitz J, Field T, Radford M, Harrold L, Becker R, Reed G, et al. The safety of warfarin therapy in the nursing home setting. Am J Med. 2007;120(6):539–44.

    Article  CAS  PubMed  Google Scholar 

  4. Abe J, Umetsu R, Kato Y, Ueda N, Nakayama Y, Suzuki Y, et al. Evaluation of dabigatran- and warfarin-associated hemorrhagic events using the FDA-adverse event reporting system database stratified by age. Int Med Sci. 2015;12(4):312–21.

    Article  Google Scholar 

  5. Seet R, Rabinstein A, Christianson T, Petty G, Brown R. Bleeding complications associated with warfarin treatment in ischemic stroke patients with atrial fibrillation: a population-based cohort study. J Stroke Cerebrovasc Dis. 2013;22(4):561–9.

    Article  PubMed  PubMed Central  Google Scholar 

  6. Alyousif S, Alsaileek A. Quality of anticoagulation control among patients with atrial fibrillation: an experience of a tertiary care center in Saudi Arabia. J Saudi Heart Assoc. 2016;28(4):239–43.

    Article  PubMed  PubMed Central  Google Scholar 

  7. Carrasco-Garrido P, de Andrés L, Barrera V, de Miguel G, Jiménez-García R. Trends of adverse drug reactions related-hospitalizations in Spain (2001–2006). BMC Health Serv Res. 2010;10(1):287.

    Article  PubMed  PubMed Central  Google Scholar 

  8. Sudlow C, Rodgers H, Kenny R, Thomson R. How to do it: service provision and use of anticoagulants in atrial fibrillation. BMJ. 1995;311:558–60.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Taylor F, Ramsay M, Renton A, Cohen H. Methods for managing the increased workload in anticoagulant clinics [letter]. BMJ. 1996;312:286.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Testa S, Zimmermann A, Cancellieri E, Bassi L, Paoletti O. Telemedicine for managing patients on oral anticoagulant therapy. In: Graschew G, Rakowsky S, editors. Telemedicine techniques and applications. 2014. ISBN: 978-953-307-354-5. www.intechopen.com.

  11. Dib J, Mohammed K, Momattin H, Alshehri A. Implementation of pharmacist-managed anticoagulation clinic in a Saudi Arabian health center. Hosp Pharm. 2014;49(3):260–8.

    Article  PubMed  PubMed Central  Google Scholar 

  12. Mayet A. Association between oral anticoagulation knowledge, anticoagulation control, and demographic characteristics of patients attending an anticoagulation clinic in Saudi Arabia: a cross-sectional prospective evaluation. Trop J Pharm Res. 2015;14(7):1285–91.

    Article  Google Scholar 

  13. Mayet A. Patient adherence to warfarin therapy and its impact on anticoagulation control. Saudi Pharm J. 2016;24(1):29–34.

    Article  PubMed  Google Scholar 

  14. Bayoumy NM, Al-Omair SF, Musallam NA, Al-Deghaither NY, Al-Sadoun NA. Compliance with and awareness about long-term oral anticoagulant therapy among Saudi patients in a university hospital, Riyadh, Saudi Arabia. J Appl Hematol. 2016;7(1):10–6.

    Article  Google Scholar 

  15. Elbur A, Albarraq A, Maugrabi M, Alharthi S. Knowledge of, satisfaction with and adherence to oral anticoagulant drugs among patients in King Fasial Hospital. Int J Pharm Sci Rev Res. 2015;31(1):274–80.

    Google Scholar 

  16. Matchar D, Jacobson A, Dolor R, Edson R, Uyeda L, Phibbs C, et al. Effect of home testing of international normalized ratio on clinical events. N Engl J Med. 2010;363(17):1608–20.

    Article  CAS  PubMed  Google Scholar 

  17. Wofford J, Wells MD, Singh S. Best strategies for patient education about anticoagulation with warfarin: a systematic review. BMC Health Serv Res. 2008;8:40.

    Article  PubMed  PubMed Central  Google Scholar 

  18. Katusiime B, Corlett S, Reeve J, Krska J. Measuring medicine-related experiences from the patient perspective: a systematic review. Patient Relat Outcome Meas. 2016;7:157–71.

    Article  PubMed  PubMed Central  Google Scholar 

  19. Nasser S, Mullan J, Bajorek B. Challenges of older patients’ knowledge about warfarin therapy. J Prim Care Commun Health. 2012;3(1):65–74.

    Article  Google Scholar 

  20. Cook DA, Beckman TJ. Current concepts in validity and reliability for psychometric instruments: theory and application. Am J Med. 2006;119(2):166.e7–16.

    Article  Google Scholar 

  21. Zeolla M. Development and validation of an instrument to determine patient knowledge: the oral anticoagulation knowledge test. Ann Pharmacother. 2006;40(4):633–8.

    Article  PubMed  Google Scholar 

  22. Briggs A, Jackson T, Bruce S, Shapiro N. The development and performance validation of a tool to assess patient anticoagulation knowledge. Res Social Adm Pharm. 2005;1(1):40–59.

    Article  PubMed  Google Scholar 

  23. Khudair I, Hanssens Y. Evaluation of patients’ knowledge on warfarin in outpatient anticoagluant clinics in a teaching hosiptal in Qatar. Saudi Med J. 2010;31(6):672–7.

    PubMed  Google Scholar 

  24. Morisky D, Green L, Levine D. Concurrent and predictive validity of a self-reported measure of medication adherence. Med Care. 1986;24(1):67–74.

    Article  CAS  PubMed  Google Scholar 

  25. Wang Y, Kong M, Ko Y. Comparison of three medication adherence measures in patients taking warfarin. J Thromb Thrombolysis. 2013;36(4):416–21.

    Article  CAS  PubMed  Google Scholar 

  26. Osterberg L, Blaschke T. Adherence to medication. N Engl J Med. 2005;353(5):487–97.

    Article  CAS  PubMed  Google Scholar 

  27. Glanz K, Scholl TO. Intervention strategies to improve adherence among hypertensives: review and recommendations. Patient Couns Health Educ. 1982;4(1):14–28.

    Article  CAS  PubMed  Google Scholar 

  28. Sweileh W, Aker O, Hamooz S. Rate of compliance among patients with diabetes mellitus and hypertension. An-Najah Univ J Res. (N. Sc.). 2005;19(1):1–11.

    Google Scholar 

  29. Jamous R, Sweileh W, Abu-Taha A, Sawalha A, Zyoud S, Morisky D. Adherence and satisfaction with oral hypoglycemic medications: a pilot study in Palestine. Int J Clin Pharm. 2011;33(6):942–8.

    Article  PubMed  Google Scholar 

  30. Morisky D, Ang A, Krousel-Wood M, Ward H. Predictive validity of a medication adherence measure in an outpatient setting. J Clin Hypertens. 2008;10(5):348–54.

    Article  Google Scholar 

  31. Wang Y, Kong M, Ko Y. Psychometric properties of the 8-item Morisky Medication Adherence Scale in patients taking warfarin. Thromb Haemost. 2012;108(4):789–95.

    Article  CAS  PubMed  Google Scholar 

  32. Schulman S, Kearon C. Definition of major bleeding in clinical investigations of antihemostatic medicinal products in non-surgical patients. J Thromb Haemost. 2005;3(4):692–4.

    Article  CAS  PubMed  Google Scholar 

  33. Hirsh J, Dalen J, Anderson D, Poller L, Bussey H, Ansell J, et al. Oral Anticoagulants: mechanism of action, clinical effectiveness, and optimal therapeutic range. Chest. 2001;119:8S–21S.

    Article  CAS  PubMed  Google Scholar 

  34. Konishi H, Miyauchi K, Kasai T, Tsuboi S, Ogita M, Naito R, et al. Adequate time in therapeutic INR range using triple antithrombotic therapy is not associated with long-term cardiovascular events and major bleeding complications after drug-eluting stent implantation. J Cardiol. 2016;68(6):517–22.

    Article  PubMed  Google Scholar 

  35. Rosendaal F, Cannegieter S, Van der Meer F, Briet E. A Method to determine the optimal intensity of oral anticoagulant therapy. Thromb Haemost. 1993;69(3):236–9.

    CAS  PubMed  Google Scholar 

  36. Rose A, Berlowitz D, Frayne S, Hylek E. Measuring Quality of Oral Anticoagulation care: extending quality measurement to a new field. Jt Comm J Qual Patient Saf. 2009;35(3):146–55.

    Article  PubMed  Google Scholar 

  37. Sargent R, Brocklebank C, Tam-Tham H, Williamson T, Quail P, Turner D, et al. Advantages of a warfarin protocol for long-term care pharmacists: a retrospective cohort study. Can Geriatr J. 2016;19(2):40–9.

    Article  PubMed  PubMed Central  Google Scholar 

  38. Verhovsek M, Motlagh B, Crowther M, Kennedy C, Dolovich L, Campbell G, et al. Quality of anticoagulation and use of warfarin-interacting medications in long-term care: a chart review. BMC Geriatr. 2008;8:13.

    Article  PubMed  PubMed Central  Google Scholar 

  39. Davis N, Billett H, Cohen H, Arnsten J. Impact of adherence, knowledge, and quality of life on anticoagulation control. Ann Pharmacother. 2005;39(4):632–6.

    Article  PubMed  Google Scholar 

  40. Esmerio F, Souza E, Leiria T, Lunelli R, Moraes M. Constant use of oral anticoagulants: implications in the control of their adequate levels. Arq Bras Cardiol. 2009;93(5):549–54.

    Article  PubMed  Google Scholar 

  41. Ryals C, Pierce K, Baker J. INR Goal attainment and oral anticoagulation knowledge of patients enrolled in an anticoagulation clinic in a veterans affairs medical center. J Manag Care Pharm. 2011;17(2):133–42.

    PubMed  Google Scholar 

  42. Barcellona D, Contu P, Marongiu F. Patient education and oral anticoagulant therapy. Haematologica. 2002;87(10):1081–6.

    PubMed  Google Scholar 

  43. Matalqah L, Radaideh K, Sulaiman S, Hassali M, Abdul Kader M. Relationship between patients’ warfarin knowledge and anticoagulation control: results of a validated tool in Malaysia. J Pharm Biomed Sci. 2013;30(30):967–74.

    Google Scholar 

  44. Kimmel S, Chen Z, Price M, Parker C, Metlay J, Christie J, et al. The Influence of patient adherence on anticoagulation control with warfarin. Arch Intern Med. 2007;167(3):229–35.

    Article  CAS  PubMed  Google Scholar 

  45. Nguyen TM, La Caze A, Cottrell N. What are validated self-report adherence scales really measuring? A systematic review. Br J Clin Pharmacol. 2014;77(3):427–45.

    Article  PubMed  PubMed Central  Google Scholar 

  46. Stirratt MJ, Dunbar-Jacob J, Crane HM, Simoni JM, Czajkowski S, Hilliard ME, et al. Self-report measures of medication adherence behavior: recommendations on optimal use. Transl Behav Med. 2015;5(4):470–82.

    Article  PubMed  PubMed Central  Google Scholar 

Download references

Acknowledgements

The authors would like to acknowledge the administrative team at the Security Forces Hospital in Riyadh for their approval and support to conduct the study. We are grateful to all patients who agreed to participate in the survey and contribute to this research, and we are grateful to all of the cardiologists at the hospital for clinical data acquisition.

Funding

There were no external funding sources for this study.

Author information

Authors and Affiliations

  1. Department of Pharmacy Practice,, Pharmacy College Princess Nourah bint Abdul Rahman University, Riyadh, 11671, P.O. Box 84428, Saudi Arabia

    Sireen Abdul Rahim Shilbayeh, Wejdan Ali Almutairi, Sarah Ahmed Alyahya, Nouf Hayef Alshammari, Eiad Shaheen & Alya Adam

Authors
  1. Sireen Abdul Rahim Shilbayeh
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Wejdan Ali Almutairi
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Sarah Ahmed Alyahya
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Nouf Hayef Alshammari
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Eiad Shaheen
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Alya Adam
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Sireen Abdul Rahim Shilbayeh.

Ethics declarations

Conflicts of interest

There are no potential conflicts of interest to report.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Shilbayeh, S.A.R., Almutairi, W.A., Alyahya, S.A. et al. Validation of knowledge and adherence assessment tools among patients on warfarin therapy in a Saudi hospital anticoagulant clinic. Int J Clin Pharm 40, 56–66 (2018). https://doi.org/10.1007/s11096-017-0569-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11096-017-0569-5

Keywords

Search

Navigation