arv adherence model
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Presentation Developed by Doreen Ofosu
3 – 5 October, 2011
Frontiers of Retrovirology2011
Presentation Developed by Doreen Ofosu
The Dose-Adherence Model:
A Critical Review of the Computation of Level of Adherence to Antiretroviral Drug Regimen
By: Doreen Ofosu Kwame Nkrumah University of Science & Technology
Kumasi, Ghana
Presentation Developed by Doreen Ofosu
Outline
• Research Objectives
• Research Background
• Literature Review
• Further Research
• Significance of Study
• The Study
Presentation Developed by Doreen Ofosu
Outline Cont'd• Questionnaire
• Resultso Result of Objective Ao Results of Objective B
• Conclusion
• Recommendation
• Bibliography
• Acknowledgment
• Further Information
Presentation Developed by Doreen Ofosu
Research Objectives
• Objective ATo develop a model for determining long-term dose-adherence
•Objective BTo determine the dose-adherence levels of ART clients in the Eastern Region of Ghana
Presentation Developed by Doreen Ofosu
Research Background
Adherence Defined• Usually taking 80% or more of the prescribed regimen. (Chesney, 1997)
• In people with HIV infection, reports of adherence range from 25% to 85%.
(Bachiller et al., 1998)
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Research Background Cont'd
HIV treatment adherence is essential
Source: YouTube Video Uploaded by Mindset Health
Presentation Developed by Doreen Ofosu
Literature Review
1. Bachiller et al., 1998... reports of adherence range from 25% - 85%.
2. Weiser et al., 2003... adherence for ARV therapy ranges from 40% to 60% with an average of 50% adherence level.
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Literature Review Cont'd
3. Haubrich et al., 1999... labeled patients as adherent if at least 80% of the prescribed doses are taken.
4. Paterson et al., 2000... it has been estimated that at least 95% of the prescribed dose is needed to maintain HIV viral suppression and to prevent the occurrence of drug resistance.
Presentation Developed by Doreen Ofosu
Further Research
• No known model for computing long-term adherence
• Sample tweets on next slide confirms this
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Tweets
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Significance of Model
Considers
• Long-term default frequency
• Short-term recall of missed doses or self-report
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The Study
• Study Populationo ART clients
• Inclusion Criteriao Must be 18 years and aboveo Must be an outpatiento Must be willing to participate
• Exclusion Criteriao Below 18 yearso Weak clients
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The Study Cont'd Ethical Considerations
• Permission sought from regional, district and facility administrations before commencement of study
• Client consent sought
• Consent form explained to client in detail
• Willing clients sign consent forms and given a copy
Presentation Developed by Doreen Ofosu
The Study Cont'd
Study Area• Eastern Region of Ghana
Facts About the Eastern Region of Ghana• Highest HIV prevalence n the country
• 2004 HIV Sentinel Survey puts HIV prevalence of the Region at 6.5% against the national figure of 3.1%
• 2008 regional prevalence 4.5% against national rate of 1.7%
Study Coverage• Fifteen of the then seventeen districts
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The Study Cont'd
Study Sites• Social support groups – eleven • Ten districts
ART facilities - three
• Regional hospital
• District hospital
• Mission hospital
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The Study Cont'd
Methodology
Study Design• Cross-sectional
Data Collection Tool• Standardized questionnaires
Data Collection Technique• Exit interviews
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Questionnaire Administration On Dose-Adherence
Questions Asked and Responses
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Questionnaire
• Q. ART duration (expected doses)A. One month to three years
• Q. Missed dosesA. Yes or no
• Q. Reasons for missing if yes A. Forgetfulness Carelessness Stopping the drug when feeling better / worse Other (Specify)
Presentation Developed by Doreen Ofosu
Questionnaire Cont'd• Q. Ever re-started if defaulted
A. Yes or no
• Q. Reasons for re-starting if yesA. I got my drugs Returned from journey I was feeling weak Frequent rashes Headaches Swellings Anxiety Frequent coughs Other (Specify)
Presentation Developed by Doreen Ofosu
Questionnaire Cont'd
• Q. Difficulty in adhering to dose regimenA. Yes or no
• Q. Frequency at which doses were missed (Default Frequency)A. Defaulted continuously for weeks Missed often Missed a few times Never missed
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Questionnaire Cont'dFrame of long-term default frequency question
• Educational level
• Occupation
Seasons Used• Religious
• Traditional
• Farming
• Fishing
• Academic calendars
• National holidays
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Results
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Result Of Objective A
The Dose-adherence model developed from
• Expected doses
• Default frequency
• Observed doses
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Results of Objective A Cont'dComputation of Expected Doses (E)
• Number of weeks on ART (ART duration) multiplied by 14
Computation of Default Frequency (Literature Based)
• 25% [1]
• 50% [2]
• 80% [3]
• 100% [4]
Respondent frequency synonymous with doses missed
Presentation Developed by Doreen Ofosu
Results of objective A Cont'd
Computation of Observed Doses (O)
• Defaulted continuously for weeks = E multiplied by 25% [1]
• Missed often = E multiplied by 50% [2]
• Missed a few times = E multiplied by 80% [3]
• Never missed = E multiplied by 100% [4]
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The Dose-Adherence Model
Presentation Developed by Doreen Ofosu
The Dose-Adherence Model
• A Mathematical Model for Determining Long-term Level of Adherence to Dose Regimen:
"Level of adherence is the ratio of the observed doses (O) and the expected doses (E)." - Ofosu et al., (2008)
Otherwise stated as:
"Level of adherence is directly proportional to the frequency at which doses are missed." - Ofosu et al., (2008)
Presentation Developed by Doreen Ofosu
The Dose-Adherence Model Cont'd
Mathematically:
• Level of Adherence (%) = O / E
•Level of Adherence (%) = Default Frequency
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Results of Objective BRespondents' statistically significant at p-value of 0.051
• 25% - 1.1% of respondents
• 50% - 1.7% of respondents
• 80% - 14.0% of respondents
• 100% - 83.2% of respondents
Presentation Developed by Doreen Ofosu
Conclusion
The Dose-Adherence Model
• Complements other methods of deducing adherence level
• Considers long-term default frequency and short-term recall
Presentation Developed by Doreen Ofosu
Recommendation
• Digitising long-term adherence computation using the Dose-adherence Model
Presentation Developed by Doreen Ofosu
Presentation Developed by Doreen Ofosu
Bibliography1. Bachiller, P., Arrando, F.R., Liceago, G., Iribarren, J.A. & Olloquiegui, E. (1998).
Drug Compliance in Patients Starting Saquinavir. 12th World AIDS Conference,Geneva, Abstract 32392.
2. Chesney, M.A. (1997). New HAART Therapies: Adherence Challenges and Strategies Evolving HIV Treatments: Advances and the Challenges of Adherence of Adherence. 37th ICAAC Symposium, Toronto, Canada.
3. Haubrich R.H., Little S.I., Currier J.S., Forthal D.N., Kemper C.A. and Beall G.N. (1999).The Value of Patient-Reported Adherence to Antiretroviral Therapy in Predicting Virologic and Immunologic Response. California Collaborative Treatment Group. AIDS; 13(9):1099-107.
4. Paterson D.L., Swindels S. & Mohr J. (2000). Adherence to Protease Inhibitor Therapy andOutcomes in Patients with HIV Infection. Annals of Internal Medicine, 133, 21A.
5. Weiser S., Wolfe W., Bangsberg D., Thior I., Gilbert P., Makhema J. (2003). Barriers toAntiretroviral Adherence for Patients Living with HIV Infection and AIDS in Botswana.Acquired Immune Deficiency Syndrome; 34(3):281-8.
6. http://twitter.com. Tweets on Drug Adherence (September, 2011).
7. http://youtube.com. HIV Treatment Adherence is Essential. Video uploaded by Mindset Health (August 5, 2009).
Presentation Developed by Doreen Ofosu
AcknowledgmentCo-Authors
• Mr. P. Agyei-Baffour (Academic Supervisor, KNUST)
• Rev. Dr. E. Browne (Fmr Head, Community Health, KNUST)
• Mr. J.A. Amankwah (Administration, KATH)
• Dr. G. Acquah-Hagan (Medical Doctor, KATH)
Special Thanks
• Dr. S.B. Ofori (Field Supervisor, Regional ART coordinator)
• Dr. Akyeampong (HIV Clinic, KATH)
Presentation Developed by Doreen Ofosu
Further Information• www.bit.ly/gi8Awh
• ww.doseadherencemodel.wordpress.com
Do You Have Questions And / Or Comments? Go to:
• http://portal.sliderocket.com/Dose-Adherence-Model-Presentation
Presentation Developed by Doreen Ofosu
www.twitter.com/icingt2
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