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A brief tool to assess capacity to consent for medical care among homeless individuals with problematic… Taylor, Darlene; Masse, Louise; Ho, Anita; Rekart, Michael L; Tyndall, Mark; Henry, Bonnie; Clifton, Joanne; Peters, Laurenna; Ogilvie, Gina; Buxton, Jane May 8, 2013

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STUDY PROTOCOL Open AccessA brief tool to assess capacity to consent formedical care among homeless individuals withproblematic substance use: study protocolDarlene Taylor1*, Louise Masse2, Anita Ho3, Michael L Rekart4, Mark Tyndall5, Bonnie Henry1, Joanne Clifton6,Laurenna Peters1, Gina Ogilvie1 and Jane Buxton1AbstractBackground: Public health care increasingly uses outreach models to engage individuals who are marginalized,many of whom misuse substances. Problematic substance use, together with marginalization from the health caresystem, among homeless adults makes it difficult to assess their capacity to consent to medical care. Tools havebeen developed to assess capacity to consent; however, these tools are lengthy and unsuitable for outreachsettings. The primary objective of this study is to develop, validate, and pilot a brief but sensitive screeninginstrument which can be used to guide clinicians in assessing capacity to consent in outreach settings. The goal ofthis paper is to outline the protocol for the development of such a tool.Methods/Design: A brief assessment tool will be developed and compared to the MacArthur CompetencyAssessment Tool for Treatment (MacCAT-T). As list of 36 possible questions will be created by using qualitative datafrom clinician interviews, as well as concepts from the literature. This list will be rated by content experts accordingto the extent that it corresponds to the test objectives. The instrument will be validated with 300 homeless adultvolunteers who self-report problematic substance use. Participants will be assessed for capacity using the MacCAT-Tand the new instrument. A combination of Classical Test Theory and advanced psychometric methods will be usedfor the psychometric analysis. Corrected Item-Total correlation will be examined to identify items that discriminatepoorly. Guided exploratory factor analysis will be conducted on the final selection of items to confirm theassumptions for a unidimensional polytomous Rasch model. If unidimensionality is confirmed, an unstandardizedCronbach Alpha will be calculated. If multi-dimensionality is detected, a multidimensional Rasch analysis will beconducted. Results from the new instrument will be compared to the total score from the MacCAT-T by usingPearson’s correlation test. The new instrument will then be piloted in real-time by street outreach clinicians todetermine the acceptability and usefulness of the new instrument.Discussion: This research will build on the existing knowledge about assessing capacity to consent and willcontribute new knowledge about assessing individuals whose judgment is impaired by substance use.Keywords: Capacity to consent, Substance use, Psychometric instruments, Vulnerable populations* Correspondence: darlene.taylor@bccdc.ca1BC Centre for Disease Control, University of British Columbia, 655 West 12thAvenue, Vancouver, BC V5Z 4R4, CanadaFull list of author information is available at the end of the articleARCHIVES OF PUBLIC HEALTH© 2013 Taylor et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the CreativeCommons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited.Taylor et al. Archives of Public Health 2013, 71:11http://www.archpublichealth.com/content/71/1/11BackgroundSubstance misuse is associated with a high prevalence ofphysical and mental co-morbidities requiring medicalcare. In 2009 there were an estimated 4,049 hospitaliza-tions as a result of illicit drug use in British Columbia(BC) Canada [1]. These data highlight the importance ofproviding prevention and treatment services to mar-ginalized groups with addictions who are particularlyvulnerable to intimidation, manipulation, coercion or ex-ploitation [2]. This population often receives care instreet outreach settings where clinician-client encountersare brief, creating complex challenges to clinicians whoattempt to obtain consent for treatment to clients whosedecision-making capacity may be impaired [3].Informed consent for treatment is defined as an “indi-vidual’s autonomous and voluntary authorization of amedical decision” for which an individual has substan-tial understanding of the risks and benefits [2]. The BCHealth Care (Consent) and Care Facility (Admission)Act [4] clearly stipulates that individuals must be capableof making rational decisions about their health and de-fines capacity as the ability to understand the medicalcare being offered (risks, benefits, and alternatives) andhow it applies to the person being offered care [4]. Thisis contrasted with an equally important right to infor-med refusal. However, the practical methods for asses-sing capacity to consent (CTC) in public health caresettings are unclear. Unlike the situation in most clinicalsettings, consent from clients in outreach settings cannotalways be implied especially when the health profes-sional seeks out clients rather than having them seekcare. In these cases, verbal consent must be obtainedand it is imperative that clinicians assess CTC before de-livering health care.Assessing impaired CTCNumerous tools have been developed to assess CTC forclinical treatment and/or research purposes. A recentsystematic review [5] provides a comprehensive assess-ment of 23 instruments for assessing CTC. The majorityof instruments have been developed for and validatedin populations with mental illness such as depression,schizophrenia, and Alzheimer’s disease and involve astructured or semi-structured interview using hypothet-ical vignettes or real decision-making scenarios that last15–90 minutes. These scales primarily focus on elementsof understanding, recall of facts, the ability to appreciatethe fact that the study or treatment involves them andthe ability to state the reason for their decision. Currentscales vary greatly in terms of standardization and sco-ring procedures.The most widely used instrument is the MacArthurCompetency Assessment Tool (MacCAT) (for treatmentor for research) which has been shown to have goodpsychometric properties and takes 15–30 minutes to ad-minister [6,7]. While these tools may be useful when theclinician has ample time to administer and score the in-strument, it is impractical in street outreach settings,where clinical encounters are typically brief.No tool, to our knowledge, has been developed to as-sess CTC among homeless individuals with problematicsubstance use. This group is unique in that some indi-viduals may be better able to give consent when they areunder the influence of a substance than when they areexperiencing withdrawal symptoms. It is recognized thathomeless adults with problematic substance use have adiminished CTC, making them vulnerable to exploita-tion [8]. Our research will address the particularly salientproblem of assessing CTC in this population.The purpose of this research study is to develop a brieftool that can be used by public health care clinicians toguide their assessment of their clients’ capacity to pro-vide informed consent for medical care when under theinfluence of substances. This study has been approvedby the University of British Columbia research ethicsboard.Research objectivesThe objectives for this study are as follows: (1) to surveyclinicians who provide services to clients who misusesubstances to determine their current practices for as-sessing capacity to consent for clinical care, (2) to ex-plore the experiences of providing consent from theperspective of people who misuse substances, and (3) todevelop a brief assessment tool with acceptable psycho-metric properties that can be used to assess CTC formedical care in outreach settings.Methods/DesignA series of qualitative interviews will be conductedamong a purposive sample of clinicians throughout BCwho deliver care to homeless clients with problematicsubstance use. Recruitment will be conducted by emailadvertisement distributed by infectious control leadersin each health authority, and sampling will be done untiltheoretical saturation is reached (estimated to be 20 par-ticipants). Maximum-variation sampling will be em-ployed, which allows exploration of both typical andunusual concepts across a broad range of settings [9].Critical social theory and decision-making theory will beused to create a semi-structured interview guide to in-terview participants about their current practice forassessing CTC, i.e., the conceptual elements they con-sider when assessing capacity, the methods they use toassess these elements, and the threshold they use tomake a final decision about capacity. Interviews will beconducted in a private office at the participant’s place ofwork.Taylor et al. Archives of Public Health 2013, 71:11 Page 2 of 4http://www.archpublichealth.com/content/71/1/11A series of qualitative interviews will also be con-ducted with a convenience sample of adults throughoutBC who are homeless and who self-report as abusingsubstances. Recruitment will be conducted throughadvertisement at community-based organizations andthrough word of mouth. Sampling will be done untiltheoretical saturation is reached (estimated to be 25 par-ticipants). The purpose of these interviews is to explorethe experience of providing consent or obtaining med-ical care from the perspective of these individuals. Powerinequities will also be explored. Interviews will be con-ducted in a private room where the community organi-zation meets. A $20 cash honorarium will be providedto participants.All interviews will be audiotaped and transcribed ver-batim without personal identifiers. Concepts and themeswill be identified in the data, and an interpretive des-cription analysis [10], using both inductive (allowingconcepts and themes to emerge from the data) and de-ductive (using concepts and themes that are described inthe literature) approaches, will be conducted to deter-mine how assessment of CTC can be translated intoclinical practice.Instrument developmentA comprehensive review of the literature will be con-ducted to examine the existing instruments for de-termining CTC. In addition, theoretical concepts relatedto CTC will be reviewed. The proposed tool will beconstructed using theoretical concepts, legal concepts,and knowledge gained from qualitative interviews. Reli-able, validated questions from existing instruments willbe added to the list of possible questions.The proposed questions will be provided to a panel ofexperts to establish item-objective congruency by ratingeach question (item) using the Osterlind method [11].The panel of experts will include four doctors and fournurses from public health, one practitioner who deliversclinical care to the target population, one lawyer, oneethicist, an addictions specialist, and a psychiatrist.Experts will be encouraged to suggest other questionswhich may have been omitted. A modified Delphi pro-cess will be used to achieve group consensus about therelevancy of each question. Questions with discordantratings will be further discussed in person until consen-sus is reached.Once a near-final version of the instrument is created,pilot testing [12] will be conducted with five individualsfrom the target population. During this process, partici-pants will be asked to respond to the questions andasked why they chose the response they chose and whatthe question meant to them. At this time, the number ofresponse options will be assessed for appropriateness.Instrument validationThree hundred clients who are more than 18 years old,and who speak and read English, self-report as beinghomeless, and self-report abuse of substances will berecruited for a validation study through a recruitmentposter placed in a downtown Vancouver community-based organization. A short questionnaire on demogra-phics, substance use, and history of mental illness will beadministered. Participants will be presented with a simu-lated consent for a hypothetical medical scenario. Theywill then be assessed by a psychiatrist to capture a clin-ical assessment of capacity. Next, participants will be ad-ministered the MacCAT for treatment (MacCat-T) toolfollowed by the administration of the new assessmenttool, conducted by a research nurse blinded to the clinicaland MacCAT-T result. A second researcher will observethe interview and score it independently and a Kappa sta-tistic [13] will be calculated using SPSS 14 to determineinter-rater reliability. A Kappa score of >0.8 will be consid-ered acceptable [14].Psychometric analysisA combination of classical test theory and advanced psy-chometric methods will be used for the psychometricanalysis. An item analysis will be conducted by examin-ing the corrected item-total correlation to identify itemsthat discriminate poorly [15,16]. Removal of items withcorrected item-total correlation of <0.20 will be consid-ered if the content is not considered clinically important.We aim to create an instrument that has the fewestitems while maintaining good psychometric properties.The minimum number of items required to provide areliability of at least 0.80 will be calculated using theSpearman Brown prophecy formula [17].Guided exploratory factor analysis will be conductedon the final selection of items to confirm the assump-tions for a Rasch model [18]. If multi-dimensionality isconfirmed multidimensional Rasch analysis will beconducted. If unidimensionality is confirmed an unstan-dardized Cronbach Alpha will be calculated and a globalsummary score will be created. The global score and theMacCAT-T score will be compared using a Pearson’scorrelation test. A cutoff value for the new instrumentwill be created by conducting a receiver operating char-acteristic analysis using a combination of the clinical as-sessment of capacity and the four domain scores fromthe MacCAT-T as the gold standard. If the clinical as-sessment and all four MacCAT-T domain scores indicatecapacity, then the gold standard assessment will be re-corded as “has capacity”. If any of these five elementsindicates a lack of capacity, then the gold standard as-sessment will be recorded as “does not have capacity”.Results will be stratified by alcohol use only, drug useonly, and mental status.Taylor et al. Archives of Public Health 2013, 71:11 Page 3 of 4http://www.archpublichealth.com/content/71/1/11DiscussionThis study will address an important component of cur-rent practice for assessing CTC to treatment among po-pulations with addictions who may have impaired CTCand thus be vulnerable to coercion. The new instrumentwill provide guidance to clinicians who deliver care toindividuals with problematic substance use who may ormay not be impaired during a clinical encounter, espe-cially encounters that occur in outreach settings. Notools, to our knowledge, have been developed to assessCTC among these vulnerable individuals. Moreover, exis-ting tools are cumbersome and may construct a barrier tocare. While the study will be conducted in outreach set-tings, it is likely that this tool will be transferable to othersettings where medical encounters with individuals im-paired by substances are brief, such as emergency rooms,emergency medical services, and community clinics.AbbreviationsBC: British Columbia; CTC: Capacity to consent; MacCAT: MacArthurcompetency assessment tool; MacCAT-T: MacArthur competency assessmenttool for treatment.Competing interestsAll authors declare that they have no competing interests.Authors’ contributionsDT was responsible for drafting the article. DT, LM, JC, GO, and JAB wereresponsible for conception and design of the study. All authors wereresponsible for critical revision of important intellectual content and approvalof the final version to be published.AcknowledgementsThis research proposal has been funded by the Canadian Institutes forHealth Research.Author details1BC Centre for Disease Control, University of British Columbia, 655 West 12thAvenue, Vancouver, BC V5Z 4R4, Canada. 2Department of Pediatrics/Schoolof Population and Public Health, University of British Columbia, 4480 OakStreet, L408, Vancouver, BC V6H 3V4, Canada. 3Centre for Applied Ethics,University of British Columbia, 6356 Agricultural Road, Vancouver, BC V6T1Z2, Canada. 4School of Population and Public Health, University of BritishColumbia, 2206 East Mall, Vancouver, BC V6T 1Z3, Canada. 5Department ofInfectious Diseases, University of Ottawa, 75 Laurier Avenue East, Ottawa, ONK1N 6N5, Canada. 6Department of Surgery, University of British Columbia,899 West 12th Avenue, Vancouver, BC V5Z 1M9, Canada.Received: 24 October 2012 Accepted: 6 May 2013Published: 8 May 2013References1. University of Victoria, Centre for Addictions Research of BC: Hospitalizationsand Deaths. http://www.bccdc.ca/NR/rdonlyres/B39C410C-F5D1-467B-A92F-B46715583404/0/BCHRSSPolicyIndicatorsReportMarch162012.pdf.2. Beauchamp T, Childress J: Principles of Biomedical Ethics. 6th edition.New York: Oxford University Press; 2009.3. Gorelick D, Pickens R, Bonkofsky F: Clincial research in substance abuse:Human subject issues. In Ethics in psychiatric research: A resource manual forhuman subjects protection. Edited by Pincus H, Lieberman J, Ferris S.Washington: American Psychiatric Association; 1999:177–194.4. BC Legislature: Health Care (Consent) and Care Facility (Admission) Act.http://www.bclaws.ca/EPLibraries/bclaws_new/document/ID/freeside/00_96181_01.5. Dunn L, Nowrangi M, Palmer B, Jeste D, Saks E: Assessing decisionalcapacity for clinical research or treatment: a review of instruments.Am J Psyc 2006, 63(8):1323–1334.6. Appelbaum P, Grisso T: MacCAR-CR: MacArthur competence assessment toolfor clinical research. Sarasota, Fla: Prefessional Resource Press; 2001.7. Grisso T, Appelbaum PS: Assessing Competence to Consent to Treatment: Aguide for physicians and other health professionals. New York: OxfordUniveristy Press; 1998.8. Kipnis S: Vulnerability in research: a bioethical taxonomy. Ethical policyissues in research involving human participants. In Ethical and PolicyIssues in Research Involving Human Participants, Volume II. Edited by theNational Bioethics Advisory Commission. Bethesda, MD: National BioethicsAdvisory Commission; 2001:G1–G13.9. Sandelowski M: Sample size in qualitative research. Res Nurs Health 1995,18:179–183.10. Thorne S, Kirkham SR, Donald-Emes J: Interpretive description: anoncategorical qualitative alternative for developing nursing knowledge.Res Nurs Health 1997, 20(2):169–177.11. Osterlind SJ: Constructing test items: Multi-choice, constructed-response,performance, and other formats. Boston: Kluwer; 1998.12. Konicki Di Ioria C: Measurement in health behaviour: Methods for researchand evaluation. San Francisco: Jossey-Bass; 2005.13. Fleiss JL, Levin B, Paik MC: (Eds): Statistical Methods for Rates and Proportions.3rd edition. New York: John Wiley & Sons; 2003.14. Landis JR, Koch GG: The measurement of observer agreement forcategorical data. Biometrics 1977, 33(1):159–174.15. Konicki C: Measurement in Health Behaviour. San Fransisco: John Wiley &Sons; 2005.16. Streiner DL, Norman GR: Health Measurement Scales: A practical guide totheir development and use. 4th edition. New York: Oxford University Press;2008.17. Stanley J: Reliability in Educational Measurement. In EducaltionalMeasurement. 2nd edition. Edited by Thorndike RL. Washington DC:American Council on Education; 1971:356–442.18. Bond TG, Fox CM: Applying the Rasch Model. 2nd edition. London:Psychology Press; 2007.doi:10.1186/0778-7367-71-11Cite this article as: Taylor et al.: A brief tool to assess capacity toconsent for medical care among homeless individuals with problematicsubstance use: study protocol. Archives of Public Health 2013 71:11.Submit your next manuscript to BioMed Centraland take full advantage of: • Convenient online submission• Thorough peer review• No space constraints or color figure charges• Immediate publication on acceptance• Inclusion in PubMed, CAS, Scopus and Google Scholar• Research which is freely available for redistributionSubmit your manuscript at www.biomedcentral.com/submitTaylor et al. Archives of Public Health 2013, 71:11 Page 4 of 4http://www.archpublichealth.com/content/71/1/11


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