LETTERS

References
1. Shah S, Elmer S, Grady C. Planning for posttrial access to antiretroviral treatment for research participants in developing countries. Am J Public Health. 2009; 99(9):1556–1562. 2. National Institutes of Health. Guidance for addressing the provision of antiretroviral treatment for trial participants following their completion of NIH funded antiretroviral treatment trials in developing countries. 2005. Available at: http://grants.nih.gov/ grants/policy/antiretroviral/index.htm. Accessed October 20, 2009. 3. Shaffer DN, Yebei VN, Ballidawa JB, et al. Equitable treatment for HIV/AIDS clinical trial participants: a focus group study of patients, clinician researchers, and administrators in western Kenya. J Med Ethics. 2006;32:55–60. 4. Posse M, Meheus F, Van Asten H, van der Ven A, Baltussen R. Barriers to access to antiretroviral treatment in developing countries: a review. Trop Med Int Health. 2008;13(7):904–913. 5. MacQueen KM, Namey E, Chilongozi DA, et al. Community perspectives on care options for HIV prevention trial participants. AIDS Care. 2007;19(4): 554–560.

SHAH AND GRADY RESPOND
Onyeabor’s letter highlighted some of the ethical complexities inherent in posttrial access. Although we agree that ethically, individuals benefiting from antiretroviral therapy should continue to receive it, the challenge for all of us involved in the ethical conduct of research is to be clear about how this should occur. Many study participants in developing countries, including those in the studies cited, understandably feel that antiretroviral treatment should be continued for life.1 Yet, in other studies, participants appeared to expect national programs to provide treatment, not necessarily the researchers themselves.2 Similar to other influential ethical guidance documents,3–6 the National Institutes of Health guidelines that apply to the studies in our sample recognize that researchers have an obligation to address the provision of posttrial antiretroviral therapy, but not an obligation to directly provide it.7 Onyeabor seems to suggest that researchers have greater obligations—namely, that researchers should provide posttrial access for participants themselves in recognition of the contributions that participants make to advancing science. Though we agree with Onyeabor that research participants certainly deserve recognition for their contributions, the nature and extent of this

recognition might justifiably vary according to the contribution made, and we would argue that participants are owed a fair share of the benefits.8 However, we do not agree that researchers necessarily bear long-term obligations to provide care after their research is over. In conducting research, researchers have many important obligations, including those to maintain scientific integrity and protect research participants. Although the relationship between a researcher and a research participant cannot last forever, researchers’ obligations to participants do not end when the last pieces of data are collected. Just as hospital physicians should engage in careful discharge planning when patients are being released from their care, we would argue that researchers have obligations to end their relationships with research participants responsibly. This obligation to help participants transition to local sources of care might increase or decrease in intensity depending on several factors, including the extent of participants’ need for assistance and dependence on the researchers, whether local sources of care exist, and how long the research relationship has lasted. More work needs to be done in this area, but we hope the findings from our study help advance a more careful understanding of what it means to conduct and conclude responsible research. j Seema Shah, JD Christine Grady, RN, PhD

References
1. Shaffer DN, Yebei VN, Ballidawa JB, et al. Equitable treatment for HIV/AIDS clinical trial participants: a focus group study of patients, clinician researchers, and administrators in western Kenya. J Med Ethics. 2006;32(1):55–60. 2. Barsdorf N, Maman S, Kass N, Slack C. Access to treatment in HIV prevention trials: Perspectives from a South African community [published online ahead of print September 27, 2009]. Dev World Bioeth. PMID: 19793135. 3. Grady C, Wagman J, Ssekubugu R, et al. Research benefits for hypothetical HIV vaccine trials: The views of Ugandans in the Rakai District. IRB. 2008;30(2):1–7. 4. World Medical Association. Declaration of Helsinki, ethical principles for medical research involving human subjects. Available at: http://www.wma.net/en/ 30publications/10policies/b3/index.html. Published 2002. Accessed November 24, 2009. 5. Nuffield Council of Bioethics. The ethics of research related to health care in developing countries. Available at: http://www.nuffieldbioethics.org/go/ourwork/ developingcountries/publication_309.html. Published 2004. Accessed November 24, 2009. 6. National Bioethics Advisory Commission. Ethical and policy issues in international research: clinical trials in developing countries, Vol 1. Available at: http:// bioethics.georgetown.edu/nbac/clinical/Vol1.pdf. Published April 2001. Accessed February 20, 2010. 7. National Institutes of Health (NIH). NIH guidance addressing the provision of antiretroviral treatment for trial participants following their completion of NIHfunded HIV antiretroviral treatment trials in developing countries. Available at: http://grants.nih.gov/grants/ policy/antiretroviral/guidance.doc. Published 2005. Accessed November 23, 2009. 8. 2001 Conference on Ethical Aspects of Research in Developing Countries. Moral standards for research in developing countries: from ‘‘reasonable availability’’ to ‘‘fair benefits.’’ Hastings Cent Rep. 2004;34(3):17–27.

About the Authors
Seema Shah is with the Department of Bioethics, Clinical Center, and the Division of AIDS, National Institutes of Health, Bethesda, MD. Christine Grady is with the Department of Bioethics, Clinical Center, National Institutes of Health. Correspondence should be sent to Ms. Seema Shah, Department of Bioethics, Building 10, Room 1C118, Clinical Center, National Institutes of Health, Bethesda, MD 20892 (e-mail: shahse@mail.nih.gov). Reprints can be ordered at http://www.ajph.org by clicking the ‘‘Reprints/Eprints’’ link. This letter was accepted November 24, 2009. doi:10.2105/AJPH.2009.188383 Note. The opinions expressed are the view of the authors and do not necessarily reflect the official policies of the Department of Health and Human Services, the National Institutes of Health, or the US government.

FLAWS IN STUDY OF FIREARM POSSESSION AND RISK FOR ASSAULT
The study by Branas et al.1 contains errors in design and execution that make it difficult to determine the meaning of their findings. Their study assessed risk for being assaulted and then shot, a compound outcome event whose second element (being shot) is not inevitable given the first (being assaulted). Persons who were assaulted but not shot are not studied. We do not know whether any association between firearm possession and their outcome measure applies to assault, to being shot given an assault, or both. The study does not control for time and place. The authors invoke stray bullets to argue that residents of Philadelphia, Pennsylvania,

Contributors
S. Shah and C. Grady contributed equally to the writing and analysis.

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are at equal risk for being shot, no matter where they are and what they are doing. This ignores the fact that violence is not randomly distributed and is unfair to Philadelphia. The control group is inappropriate, as was probably guaranteed by its selection from all adult Philadelphians. There were large differences between case participants and control participants in prior criminal history and alcohol or drug involvement, all of which influence gun-carrying behavior and risk for violent victimization. Personal and geographic differences compounded one another: 83% of shootings occurred outdoors, yet while those shootings were occuring, 91% of control participants, arguably at lower risk already for personal reasons, were indoors. A list could easily be made of likely differences between case participants and control participants that were not addressed. The problems with geography and control selection are not insurmountable. A classic study of alcohol use among adult pedestrian fatalities in Manhattan enrolled the first 4 pedestrians reaching the site where the fatality occurred ‘‘on a subsequent date, but on the same day of the week and at a time as close as possible to the exact time of day of the accident [italics retained]’’2(p657) as control participants for each case participant. Branas et al. have omitted critical detail from their results. Assaults can be independent of any prior relationship between perpetrator and victim—a would-be robber spies a prospect emerging from a bar—or can occur in the context of, and perhaps because of, some prior relationship. The association between gun possession and risk of being assaulted or shot may differ greatly between these 2 types of encounters. Attacks by strangers are common, accounting for 50.5% of robberies and aggravated assaults reported by males and 34.7% of those reported by females.3 The authors should present separate results for assaults independent of and related to prior personal involvement between victims and shooters. j Garen Wintemute, MD, MPH

Correspondence should be sent to Garen Wintemute, MD, MPH, Western Fairs Building, UC Davis Medical Center, 2315 Stockton Blvd, Sacramento, CA 95817 (e-mail: gjwintemute@ucdavis.edu). Reprints can be ordered at http://www.ajph.org by clicking the ‘‘Reprints/Eprints’’ link. This letter was accepted November 15, 2009. doi:10.2105/AJPH.2009.187476

References
1. Branas CC, Richmond TS, Culhane DP, Ten Have TR, Wiebe DJ. Investigating the link between gun possession and gun assault. Am J Public Health. 2009; 99(11):2034–2040. 2. Haddon Jr W, Valien P, McCarroll JR, Umberger CJ. A controlled investigation of the characteristics of adult pedestrians fatally injured by motor vehicles in Manhattan. J Chronic Dis. 1961;14:655–678. 3. Rand MR. Criminal Victimization, 2008. Washington, DC: Bureau of Justice Statistics, 2009. NCJ number: 227777.

BRANAS ET AL. RESPOND
We are grateful for Wintemute’s comment and the opportunity to address the areas of our research about which he was unclear. We designed and executed a case–control study that was different than the study suggested by Wintemute, but that does not mean it was erroneous.1 Our study did indeed control for both time and place and included an appropriate, population-based control group that improved on the shortcomings of prior, related case–control work.1,2 Assaults not involving gun injury have the potential to go undetected by police and hospitals. Our case detection system likely missed few, if any, shootings in Philadelphia, Pennsylvania, over the study period. Wintemute is correct that the association we observed applies to either an increased risk of assault or an increased risk of being shot given an assault. This raises an important, but different, etiologic question to subsequently pursue, given the overall association between gun possession and gun assault that we observed. Because appropriate assumptions regarding the etiologically relevant timing between short-lived exposures and acute outcomes are important to avoid biases,3 we controlled for time through a common risk set sampling approach.1,3–10 We also controlled for place with 7 confounders including being indoors versus outdoors and numerous neighborhood characteristics. We did not ‘‘unfairly’’ assume that violence was randomly

distributed across Philadelphia, but rather that Philadelphians were not somehow immune from being shot based on their location and that their risk changed depending on factors for which we statistically controlled. Stray bullets were just 1 argument in support of this; we also argued that guns were mobile and could be carried into practically any neighborhood street, home, or workplace environment in Philadelphia. Ours was not a study of pedestrian injury where being indoors would have essentially eliminated the risk of being hit by a car.3 Restricting our analyses to cases in which victim and shooter were thought to have some prior involvement produced an odds ratio (OR) of 9.30 (P = .03) under the same full model specification. Cases in which victim and shooter were thought to have no prior involvement produced an OR of 4.28 (P = .40). This remains consistent with our conservative interpretation that, on average, urban gun possession was not protective. Built on prior work, our study has contributed to understanding the link between gun possession and gun assault. Future studies employing similar, and alternative, designs are certainly in order to address new research questions which follow from our work. j

Charles C. Branas, PhD Therese S. Richmond, PhD, CRNP Dennis P. Culhane, PhD Thomas R. Ten Have, PhD, MPH Douglas J. Wiebe, PhD

About the Authors
Charles C. Branas, Thomas R. Ten Have, and Douglas J. Wiebe are with the School of Medicine, University of Pennsylvania, Philadelphia. Therese S. Richmond is with the School of Nursing, University of Pennsylvania, Philadelphia. Dennis P. Culhane is with the School of Social Policy and Practice, University of Pennsylvania, Philadelphia. Correspondence should be sent to Charles C. Branas, PhD, Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA 19104 (e-mail: cbranas@ upenn.edu). Reprints can be ordered at http://www.ajph.org by clicking the ‘‘Reprints/Eprints’’ link. This letter was accepted November 25, 2009. doi:10.2105/AJPH.2009.188045

About the Author
Garen Wintemute is with the Violence Prevention Research Program, Department of Emergency Medicine, University of California, Davis.

Contributors
C. C. Branas oversaw, analyzed, and wrote this letter. T. S. Richmond and D. P. Culhane advised and assisted

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with writing. T. R. Ten Have and D. J. Wiebe advised, analyzed, and also assisted with writing.

References
1. Rothman KJ, Greenland S, eds. Modern Epidemiology. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 1999:96–99. 2. Wiebe DJ, Branas CC. Bias when using dead controls to study handgun purchase as a risk factor for violent death. Inj Prev. 2003;9(4):381–382. 3. Roberts I. Methodologic issues in injury case-control studies. Inj Prev. 1995;1(1):45–48. 4. Roberts I, Lee-Joe T. Effect of exposure measurement error in a case-control study of child pedestrian injuries. Epidemiology. 1993;4(5):477–479. 5. Hutchinson AF, Ghimire AK, Thompson MA, et al. A community-based, time-matched, case-control study of respiratory viruses and exacerbations of COPD. Respir Med. 2007;101(12):2472–2481. 6. Viboud C, Boelle PY, Kelly J, et al. Comparison ¨ of the statistical efficiency of case-crossover and casecontrol designs: application to severe cutaneous adverse reactions. J Clin Epidemiol. 2001;54(12): 1218–1227. 7. Hennessy S, Leonard CE, Newcomb C, Kimmel SE, Bilker WB. Cisapride and ventricular arrhythmia. Br J Clin Pharmacol. 2008;66(3):375–385. 8. Powell KE, Kresnow MJ, Mercy JA, et al. Alcohol consumption and nearly lethal suicide attempts. Suicide Life Threat Behav. 2001;32(suppl 1):30–41. 9. Niccolai LM, Ogden LG, Muehlenbein CE, Dziura ´ JD, Vazquez M, Shapiro ED. Methodological issues in design and analysis of a matched case-control study of a vaccine’s effectiveness. J Clin Epidemiol. 2007;60(11): 1127–1131. 10. Newman SC. Causal analysis of case-control data. Epidemiol Perspect Innov. 2006;3(Jan 27):2.

TABLE 1—Characteristics of Methamphetamine Injectors (n = 48) Who Completed a Baseline Interview, Overall and by Text Message Preference: Safe Point Study, Portland, OR, 2008–2009
Participantsa Indicating They Were Reachable by Text Messaging Participantsa (n = 48), % or Median (Range) Female White High school education or less Monthly income £ $400 Live more than 1 place in past 60 d Age, y a Yes (n = 35), % or Median (Range) 43 83 71 38 49 43 (21–61)

No (n = 13), % or Median (Range) 31 77 69 31 46 40 (20–57)

40 81 71 36 48 42 (20–61)

Participants were methamphetamine injectors who did not regularly visit a syringe exchange program themselves but received syringes from others who did attend a syringe exchange program.

USING TEXT MESSAGING TO CONTACT DIFFICULT-TO-REACH STUDY PARTICIPANTS
Kharbanda et al.1 recently discussed the potential use of text messaging for immunization reminders. In addition to investigating how text messaging could improve this and other health-related outcomes,2 we recommend researchers consider using it for contacting study participants expected to be difficult to reach. In our study ‘‘Safe Point,’’ we pilot-tested a program that trained secondary exchangers—methamphetamine injectors who frequent our syringe exchange program and regularly provide syringes to others—to be peer educators who delivered HIV risk reduction messages to methamphetamine-injecting recipients who do not regularly attend syringe exchange programs. Our evaluation involved

baseline and 3-month follow-up interviews with recipients identified by secondary exchangers. Forty-eight (75%) of 64 recipients who were eligible completed a baseline interview. All of these participants reported having injected methamphetamine within the past 60 days. Their drug use and other characteristics suggested that they would be difficult to reach (Table 1). Text messaging was an important way to reach enrolled participants during the study. Thirty-five (73%) indicated text messaging was a way to reach them—these participants appeared similar to the others (Table 1). Generally, study staff first tried to reach participants by calling them, and then tried text messaging, if possible. Staff attempted to reach 15 (31%) of the 48 enrolled participants by text messaging, and 8 of them (53%) responded to the text. Text messaging was the only way for staff to contact 3 participants at at least 1 point during the study. Overall, 43 (90%) of the 48 enrolled participants completed 3-month follow-up interviews. Five were not interviewed at follow-up: 3 were incarcerated, we had safety concerns in regard to 1 participant, and we were unable to reach the fifth participant. Based on staff reports, participants who were reached by text messaging found it acceptable. Indeed, some seemed to prefer it, possibly because text messaging requires less of a time commitment, can be more private when others are present, and can feel less personal. Text

messages also seemed easier to retrieve than did voice mail, and participants who responded to text messages did so within a day but often responded to phone messages less quickly. Last, study staff kept text messages sent to participants generic to maintain confidentiality (e.g., ‘‘Please contact Susie at [phone number]’’), and participants did not report confidentiality concerns. Text messaging was an acceptable means of communication for study participants and much cheaper than in-person field visits to participants. Given our success with text messaging and its extensive use,3 we recommend other studies consider using it as part of their comprehensive tracking protocol4 for contacting populations expected to be difficult to reach. j Julie E. Maher, PhD Kathryn Pranian, BA Linda Drach, MPH Maureen Rumptz, PhD Carol Casciato, BA Jessica Guernsey, MPH

About the Authors
Julie E. Maher, Linda Drach, and Maureen Rumptz are with Program Design and Evaluation Services, Multnomah County Health Department and Oregon Public Health Division, Portland. Kathryn Pranian, Carol Casciato, and Jessica Guernsey are with the HIV and Hepatitis C Community Prevention Programs, Multnomah County Health Department, Portland. Correspondence should be sent to Julie E. Maher, Program Design and Evaluation Services, Multnomah County Health

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