Proven research expertise
The Optum® HEOR ID research team has designed and conducted studies to support products for HIV, hepatitis, other viral and bacterial infections and vaccine-preventable diseases, leading to numerous conference presentations and publications in top clinical journals.
Researchers on the ID team have a broad range of backgrounds and expertise, including HEOR, epidemiology, geriatrics, pharmacy benefit management, biostatistics, public health and basic science research.
Thompson D, Oster G, McGarry LJ, Klein JO. Management of otitis media among children in a large health insurance plan. Pediatr Infect Dis J. 1999;18(3):239-244.
Poordad F, Theodore D, Sullivan J, Grotzinger K. Medical resource utilisation and healthcare costs in patients with chronic hepatitis C viral infection and thrombocytopenia. J Med Econ. 2011;14(2):194-206.
Poordad F, Theodore D, Sullivan J, Grotzinger K. Evaluating medical resource utilization and costs associated with thrombocytopenia in chronic liver disease patients. J Med Econ. 2012;15(1):112-24.
Hammond E, Trenz H, Wang X, Tummala R, Desta B, Halpern R. Validation of Systemic Lupus Erythematosus (SLE) Diagnosis in Claims Data Using Electronic Health Records (EHR). Pharmacoepidemiology and Drug Safety. 2017; 26:445-46.
Coughlin CM, Nelson M, Merchant S, Gondek K. Costs of broad-spectrum antibiotic use for acute sinusitis, chronic bronchitis, and pneumonia in a managed care population. Manag Care Interface. 2003 Jun;16(6):34-40, 55.
Goldie SJ, Grima D, Kohli M, Wright TC, Weinstein M, Franco E. A comprehensive natural history model of HPV infection and cervical cancer to estimate the clinical impact of a prophylactic HPV‐16/18 vaccine. Int J Cancer. 2003 Oct 10;106(6):896-904.
Kohli M, Ferko N, Martin A, Franco EL, Jenkins D, Gallivan S, Sherlaw-Johnson C, Drummond M. Estimating the long-term impact of a prophylactic human papillomavirus 16/18 vaccine on the burden of cervical cancer in the UK. Br J Cancer. 2007 Jan;96(1):143-50.
Ye X, Sikirica V, Schein JR, Grant R, Zarotsky V, Doshi D, Benson CJ, Riedel AA. Treatment failure rates and health care utilization and costs among patients with community-acquired pneumonia treated with levofloxacin or macrolides in an outpatient setting: A retrospective claims database analysis. Clin Ther. 2008 Feb;30(2):358-71.
Rogoza RM, Ferko N, Bentley J, Meijer CJ, Berkhof J, Wang KL, Downs L, Smith JS, Franco EL. Optimization of primary and secondary cervical cancer prevention strategies in an era of cervical cancer vaccination: a multi-regional health economic analysis. Vaccine. 2008 Sep 15;26 Suppl 5:F46-58.
Siddiqui J, Phillips AL, Freedland ES, Sklar AR, Darkow T, Harley CR. Prevalence and cost of HIV-associated weight loss in a managed care population. Curr Med Res Opin. 2009 May 1;25(5):1307-17.
O'Sullivan AK, Pandya A, Papadopoulos G, Thompson D, Langston A, Perfect J, Weinstein MC. Cost-effectiveness of posaconazole versus fluconazole or itraconazole in the prevention of invasive fungal infections among neutropenic patients in the United States. Value Health. 2009 Jul-Aug;12(5):666-73.
Frytak J, Henk HJ, De Castro CM, Halpern R, Nelson M. Estimation of economic costs associated with transfusion dependence in adults with MDS. Curr Med Res Opin. 2009 Aug;25(8):1941-51.
Stewart DL, Romero JR, Buysman EK, Fernandes AW, Mahadevia PJ. Total healthcare costs in the United States for preterm infants with respiratory syncytial virus lower respiratory infection in the first year of life requiring medical attention. Curr Med Res Opin. 2009 Nov; 25(11):2795-804.
Brixner DI, Ye X, Chu TC, Blumentals WA, Hassanein TI. . Treatment persistence in and cost of therapy for patients with chronic hepatitis C: Peginterferon alfa-2a plus ribavirin versus peginterferon alfa-2b plus ribavirin. Am J Health Syst Pharm. 2009 Dec 15;66(24):2171-78.
Rubin JL, McGarry LJ, Klugman KP, Strutton DR, Gilmore KE, Weinstein MC. Public health and economic impact of vaccination with 7-valent pneumococcal vaccine (PCV7) in the context of the annual influenza epidemic and a severe influenza pandemic. BMC Infect Dis. 2010 Jan;10:14.
McGarry LJ, Merchant S, Nathwani D, Pawar V, Delong K, Thompson D, Akhras K, Ingham M, Weinstein MC. Economic assessment of doripenem versus imipenem in the treatment of ventilator-associated pneumonia. J Med Econ. 2010 Mar;13(1):142-47.
Weiss T, Zimet G, Rosenthal S, Brenneman S, Klein J. HPV vaccination of males: Attitudes and perceptions of physicians who vaccinate females. J Adolesc Health. 2010 Jul;47(1)3-11.
Zimet GD, Weiss TW, Rosenthal SL, Good MB, Vichnin MD. Reasons for non-vaccination against HPV and future vaccination intentions among 19-26 year-old women. BMC Women’s Health. 2010 Sep 1;10:27.
Rubin JL, McGarry LJ, Strutton DR, Klugman KP, Pelton SI, Gilmore KE, Weinstein MC. Public health and economic impact of the 13-valent pneumococcal conjugate vaccine (PCV13) in the United States. Vaccine. 2010 Nov 10;28(48):7634-43.
Contreras-Hernandez I, Becker D, Chancellor J, Kuhne F, Mould-Quevedo J, Vega G, Marfatia S. Cost-effectiveness of maraviroc for antiretroviral treatment-experienced HIV-infected individuals in Mexico. Value Health. 2010 Dec;13(8):903-14.
Rosenthal SL, Weiss TW, Zimet GD, Ma L, Good MB, Vichnin MD. Predictors of HPV vaccine uptake among women aged 19–26: Importance of a physician’s recommendation. Vaccine. 2011 Jan 29;29(5):890-95.
Zimet GD, Stupiansky NW, Weiss TW, Rosenthal SL, Good MB, Vichnin M. Influence of patient’s relationship status and HPV history on physicians’ decisions to recommend HPV vaccination. Vaccine. 2011 Jan;29(3):378-81.
O'Sullivan AK, Sullivan J, Higuchi K, Montgomery B. Health care utilization & costs For cystic fibrosis patients with pulmonary infections. Manag Care. 2011 Feb;20(2):37-44.
Zimet G, Weiss T, Rosenthal S, Brenneman S, Klein J. Physician's sexual health discussions with adolescent males and attitudes about HPV vaccination. J Adolesc Health Care. 2011 Feb;48(2):S27-28.
McGarry L, Davis GL, Younossi ZM, Pawar V, Rubin J, Parekh H, Weinstein M. The impact of birth-cohort screening for hepatitis C virus (HCV) compared with current risk-based screening on lifetime incidence of and mortality from advanced liver disease (AdvLD) in the United States. Gastroenterology. 2011 May;140(5):S-890.
Westra TA, Rozenbaum MH, Rogoza RM, Nijman HW, Daemen T, Postma MJ, Wilschut JC. Until which age should women be vaccinated against HPV infection? Recommendation based on cost-effectiveness analyses. J Infect Dis. 2011 Aug 1;204(3):377-84.
Clements KM, Chancellor J, Nichol K, Delong K, Thompson D. Cost-effectiveness of a recommendation of universal mass vaccination for seasonal influenza in the United States. Value Health. 2011 Sep-Oct;14(6):800-11.
McAdam-Marx C, McGarry LJ, Hane CA, Biskupiak J, Deniz B, Brixner DI. . All-cause and incremental per patient per year cost associated with chronic hepatitis C virus and associated liver complications in the United States: A managed care perspective. J Manag Care Pharm. 2011 Sep;17(7):531-46.
O'Sullivan AK, Weinstein MC, Pandya A, Thompson D, Langston AA, Perfect JR, Papadopoulos G. Cost-effectiveness of posaconazole versus fluconazole for prevention of invasive fungal infections in US patients with graft-versus-host disease. Am J Health Syst Pharm. 2012 Jan 15;69:149-56.
Krishnarajah G, Davis EJ, Fan Y, Standaert BA, Buikema AR. Rotavirus vaccine series completion and adherence to vaccination schedules among infants in managed care in the United States. Vaccine. 2012 May;30(24):3717-22.
McGarry LJ, Pawar VS, Panchmatia HR, Rubin JL, Davis GL, Younossi ZM, Capretta JG, O’Grady MJ, Weinstein MC. Economic model of a birth cohort screening program for hepatitis C virus. Hepatology. 2012 May;55(5):1344-55.
Strutton DR, Farkouh RA, Rubin JL, McGarry LJ, Loiacono PM, Klugman KP, Pelton SI, Gilmore KE, Weinstein MC. Modeling the impact of the 13-valent pneumococcal conjugate vaccine serotype catch-up program using United States claims data. BMC Infect Dis. 2012 Aug 3;12:175.
Dodds Ashley E, Drew R, Johnson M, Danna R, Dabrowski D, Walker V, Prasad M, Alexander B, Papadopoulos G, Perfect J. Cost of invasive fungal infections in the era of new diagnostics and expanded treatment options. Pharmacotherapy. 2012 Oct;32(10):890–901.
Kohli M, Lawrence D, Haig J, Anonychuk A, Demarteau N. Modeling the impact of the difference in cross-protection data between a human papillomavirus (HPA)-16/18 AS04-adjuvanted vaccine and a human papillomavirus (HPV)-6/11/16/18 vaccine in Canada. BMC Public Health. 2012 Oct;12:872.
Gordon SC, Pockros PJ, Terrault NA, Hoop RS, Buikema AR, Nerenz D, Hamzeh FM. Impact of disease severity on healthcare costs in patients with chronic hepatitis C (CHC) virus infection. Hepatology. 2012 Nov;56(5):1651-60.
Han SH, Jing W, Mena E, Li M, Pinsky B, Tang H, Hebden T, Juday T. Adherence, persistence, healthcare utilization, and cost benefits of guideline-recommended hepatitis B pharmacotherapy. J Med Econ. 2012 Dec 1;15(6):1159-66.
Sato R, Gomez Rey G, Nelson S, Pinsky B. Community-acquired pneumonia episode costs by age and risk in commercially insured US adults aged >/=50 years. Appl Health Econ Health Policy. 2013 Jun;11(3):251-58.
Gordon SC, Hamzeh FM, Pockros PJ, Hoop RS, Buikema AR, Korner EJ, Terrault NA. Hepatitis C virus therapy is associated with lower health care costs not only in noncirrhotic patients but also in patients with end-stage liver disease. Aliment Pharmacol Ther. 2013 Oct;38(7):784-93.
Stewart DL, Ryan KJ, Seare JG, Pinsky B, Becker L, Frogel M. Association of RSV-related hospitalization and non-compliance with Palivizumab among commercially insured infants: a retrospective claims analysis. BMC Infect Dis. 2013 Dec;13(1):334.
McGarry LJ, Krishnarajah G, Hill G, Masseria C, Skornicki M, Pruttivarasin N, Arondekar B, Roiz J, Pelton SI, Weinstein MC. Cost-effectiveness of Tdap vaccination of adults aged ≥ 65 years in the prevention of pertussis in the US: A dynamic model of disease transmission. PLoS One. 2014 Jan 9;9(1):e72723.
LaMori JC, Forlenza JB, Nelson S, Cao F, Liu F, Song R, Tandon N, Buikema AR. Sustained Virologic Response (SVR) and Liver Disease Progression After Hepatitis C Virus (HCV) Treatment Initiation: A Real World Analysis Using a Large Electronic Health Record (EHR) Database. Gastroenterology. 2015;148(4):S1098.
Masseria C, Buikema A, Liu F, Krishnarajah G. Mixing of diphtheria, tetanus, and acellular pertussis (DTaP) vaccines in a population of children in managed care. Hum Vaccin Immunother. 2015 May 4;11(5):1175-83.
Kohli M, Farkouh RA, Maschio MJ, McGarry LJ, Strutton DR, Weinstein MC. Despite high cost, improved pneumococcal vaccine expected to return 10-year net savings of $12 billion. Health Aff (Millwood). 2015 Jul;34(7):1234-40.
Crown WH, Chang J, Olson M, Kahler K, Swindle J, Buzinec P, Shah N, Borah B. Can statistical linkage of missing variables reduce bias in treatment effect estimates in comparative effectiveness research studies? J Comp Eff Res. 2015 Sep;4(5):455-63.
Chit A, Becker DL, Diazgranados CA, Maschio M, Yau E, Drummond M. High-dose inactivated influenza vaccine can reduce costs and improve outcomes compared to standard-dose inactivated influenza vaccine in Canadian seniors. Value Health. 2015 Nov;18(7):A587-88.
Kauf TL, McKinnon P, Corey GR, Bedolla J, Riska PF, Sims M, Jauregui-Peredo L, Friedman B, Hoehns JD, Mercier RC, Garcia-Diaz J, Brenneman SK, Ng D, Lodise T. An open-label, pragmatic, randomized controlled clinical trial to evaluate the comparative effectiveness of daptomycin versus vancomycin for the treatment of complicated skin and skin structure infection. BMC Infect Dis. 2015 Nov 7;15:503.
Becker DL, Chit A, DiazGranados CA, Maschio M, Yau E, Drummond M. High-dose inactivated influenza vaccine is associated with cost savings and better outcomes compared to standard-dose inactivated influenza vaccine in Canadian seniors. Hum Vaccin Immunother. 2016 Dec;12(12):3036-42.
Chit A, Becker DL, DiazGranados CA, Maschio M, Yau E, Drummond M. Cost-effectiveness of high-dose versus standard-dose inactivated influenza vaccine in adults aged 65 years and older: an economic evaluation of data from a randomized controlled trial. Lancet Infect Dis. 2015 Dec;15(12):1459-66.
Hull M, Puenpatom A, McPheeters J, Schwebke K. Sustained virologic response among patients with genotype 1 hepatitis C treated with interferon-free direct-acting antiviral regimens. J Hepatol. 2016 Apr;64(2):S798.
Puenpatom A, Hull M, McPheeters J, Schwebke K. Characteristics and prevalence of chronic kidney disease among patients with hepatitis C who are treated with interferon-free direct-acting antiviral regimens. J Hepatol. 2016 Apr;64(2):S744.
Maiese EM, Johnson PT, Bancroft T, Goolsby Hunter A, Wu AW. Quality of life of HIV-infected patients who switch antiretroviral medication due to side effects or other reasons. Curr Med Res Opin. 2016 Dec;32(12):2039-46.
Mao J, Mcpheeters J, Zhang D, Acosta C, Finelli L. Herpes zoster incidence and disease burden among patients underwent autologous hematopoietic stem cell transplant 2006-2011 in a large, insured US population. Open Forum Infectious Diseases. 2016 Dec 1;3(1):2345.
Masseria C, Martin C, Krishnarajah G, Becker L, Buikema A, Tan T. Incidence and burden of pertussis among infants less than 1 year of age. Pediatr Infect Dis J. 2017 Mar;36(3):e54-e61.
Liou I, Nguyen MH, Lim JK, Shreay S, Tran JN, Dusheiko G, Gordon SR. Longitudinal changes in renal function and comorbidities in treatment-naïve and treatment- experienced chronic hepatitis B patients in an US insured population: analysis of a real-world cohort with long-term follow-up. Gastroenterology. 2017;152(5):S1087-88.
Thommes EW, Kruse M, Kohli M, Sharma R, Noorduyn SG. Review of seasonal influenza in Canada: Burden of disease and the cost-effectiveness of quadrivalent inactivated influenza vaccines. Hum Vaccin Immunother. 2017 Apr 3;13(4):867-76.
Goolsby Hunter A, Rosenblatt L, Patel C, Blauer-Peterson C, Anduze-Faris B. Clinical characteristics, healthcare costs, and resource utilization in hepatitis C vary by genotype. Curr Med Res Opin. 2017 May;33(5):829-36.
Puenpatom A, Hull M, McPheeters J, Schwebke K. Disease burden, early discontinuation, and healthcare costs in hepatitis C patients with and without chronic kidney disease treated with interferon-free direct-acting antiviral regimens. Clin Drug Investig. 2017 Jul;37(7):687-97.
Rosenblatt L, Buikema AR, Seare J, Bengtson LG, Johnson J, Cao F, Villasis-Keever A. Economic outcomes of first-line regimen switching among stable patients with HIV. J Manag Care Spec Pharm. 2017 Jul;23(7):725-34.
Puenpatom A, Hull M, McPheeters J, Schwebke K. Treatment discontinuation, adherence, and real-world effectiveness among patients treated with ledipasvir/sofosbuvir in the United States. Infect Dis Ther. 2017 Sep;6(3):423-33.
Mao J, McPheeters JT, Zhang D, Acosta C, Finelli L. Herpes zoster incidence and disease burden among patients undergoing autologous hematopoietic stem cell transplant in a large US population. Curr Med Res Opin. 2017 Oct;25:1-9.
Mao J, McPheeters JT, Finelli L. Healthcare utilization and costs among patients with herpes zoster and solid tumor malignancy on chemotherapy: a retrospective cohort study. Medicine (Baltimore). 2017 Dec; 96(48):e8746.
Mao J, McPheeters JT, Zhang D, Acosta C, Finelli L. Herpes zoster incidence and cost in patients receiving autologous hematopoietic stem-cell transplant. Curr Med Res Opin. 2018 Apr;34(4):741-49.
Johnson K, Brenneman SK, Newransky C, Sheffler-Collins S, Becker LK, Belland A, Acosta CJ. A cross-sectional survey of work and income loss consideration among patients with herpes zoster when completing a quality of life questionnaire. BMC Health Serv Res. 2018 Aug 25;18(1):662.
Tandon N, Mao J, Shprecher A, Anderson AJ, Cao F, Jiao X, Brown K. Compliance with clinical guidelines and adherence to antiretroviral therapy among patients living with HIV. Curr Med Res Opin. 2019 Jan;35(1):63-71.
Mao J, Johnson MP, McPheeters JT, Prajapati G, Beyer AP. Healthcare resource utilization and costs in patients with HIV-1 who switched first-line antiretroviral therapy. Curr Med Res Opin. 2019 Jul 5;35(11):1945-53.
An J, Lee JS, Sharpsten L, Wilson AK, Cao F, Tran JN. Impact of pill burden on adherence to hepatitis C medication. Curr Med Res Opin. 25 Sept 2019;35(11):1937-44.
Kullar R, Puzniak LA, Swindle JP, Lodise T. Retrospective real-world evaluation of outcomes in patients with skin and soft structure infections treated with tedizolid in an outpatient setting. Infect Dis Ther. 2020;9(1):107-17.
Priest J, Burton T, Blauer-Peterson C, Andrade K, Oglesby A. Clinical Characteristics and Treatment Patterns Among US Patients With HIV. Am J Manag Care. 2019 Dec;25(12):580-586.
Paudel M, Mahmud S, Buikema AR, Korrer S, Van Voorhis D, Brekke L, Chit A. Relative vaccine efficacy of high-dose versus standard-dose influenza vaccines in preventing influenza in a Medicare Fee-for-Service population. Vaccine. 2020 Jun 15;38(29):4548-4556. doi: 10.1016/j.vaccine.2020.05.020. Epub 2020 May 20.
Tran JN, Wong RJ, Lee JS, Bancroft T, Buikema AR, Ting J, Terrault N. Hepatitis C Screening Rates and Care Cascade in a Large US Insured Population, 2010–2016: Gaps to Elimination. Popul Health Manag. 2021 Apr;24(2):198-206. doi: 10.1089/pop.2019.0237. Epub 2020 May 11
Ghaswalla P, Bengtson LGS, Marshall GS, Buikema AR, Bancroft T, Schladweiler KM, Koep E, Novy P, Hogea CS. Meningococcal vaccination in patients with newly diagnosed asplenia in the United States. Vaccine. 2021 Jan 8;39(2):272-281. doi: 10.1016/j.vaccine.2020.11.068. Epub 2020 Dec 10.
Brakenridge SC, Wilfret DA, Maislin G, Andrade KE, Walker V, May AK, Dankner WM, Bulger EM. Resolution of Organ Dysfunction as a Predictor of Long-Term Survival in Necrotizing Soft Tissue Infections: Analysis of the ACCUTE Trial and a Retrospective Claims-Linked Database Study. J Trauma Acute Care Surg. 2021 Aug 1;91(2):384-392.
Buikema AR, Buzinec P, Paudel ML, Andrade K, Johnson JC, Edmonds YM, Jhamb SK, Chastek B, Raja H, Cao F, Hulbert E, Korrer S, Mazumder D, Seare J, Solow BK, Currie UM. . Racial and ethnic disparity in clinical outcomes among patients with confirmed COVID-19 infection in a large US electronic health record database. EClinical Medicine. 2021 Sep;39:101075. doi: 10.1016/j.eclinm.2021.101075. Epub 2021 Sep 3.
Marshall GS, Ghaswalla PK, Bengtson LGS, Buikema AR, Bancroft T, Koep E, Novy P, Hogea CS. Low meningococcal vaccination rates among patients with newly diagnosed complement component deficiencies in the United States. Clin Infect Dis. 2022 Aug 24;75(1):155-158. doi: 10.1093/cid/ciab917.
Priest J, Hulbert E, Gilliam BL, Burton T. Characterization of Heavily Treatment-Experienced People with HIV and Impact on Healthcare Resource Utilization in US Commercial and Medicare Advantage Health Plans. Open Forum Infectious Diseases. 2021 Nov 6;8(12):ofab562. doi: 10.1093/ofid/ofab562. eCollection 2021 Dec.
Majethia S, Lee IH, Chastek B, Bunner S, Wolf J, Hsiao A, Mozaffari E. Economic impact of applying the AASLD-IDSA simplified treatment algorithm on the real-world management of hepatitis C. J Manag Care Spec Phar. 2022 Jan;28(1):48-57. doi: 10.18553/jmcp.2021.21246. Epub 2021 Oct 22.
Ghaswalla PK, Marshall GS, Bengtson LGS, Buikema AR, Bancroft T, Koep E, Novy P, Hogea CS. Meningococcal Vaccination Rates Among People With a New Diagnosis of HIV Infection in the US. JAMA Netw Open. 2022;5(4):e228573. doi:10.1001/jamanetworkopen.2022.8573
Nguyen MH, Roberts LR, Engel-Nitz NM, Bancroft T, Ozbay AB, Singal AG. Gaps in hepatocellular carcinoma surveillance in a United States cohort of insured patients with cirrhosis. Curr Med Res Opin. 2022 Dec;38(12):2163-2173. doi: 10.1080/03007995.2022.2124070. Epub 2022 Sep 22
Nguyen MH, Roberts LR, Engel-Nitz NM, Bancroft T, Ozbay AB, Singal AG. Gaps in hepatocellular carcinoma surveillance among insured patients with hepatitis B infection without cirrhosis in the United States. 2022 Dec;6(12):3443-3456. doi: 10.1002/hep4.2087. Epub 2022 Sep 30.
Fisher L, Loiacono MM, Payne N, Kelley T, Greenberg M, Charpentier M, Leblanc C, Sundaresan D, Bancroft T, Steffens A, Paudel M. A novel household-based patient outreach pilot program to boost late-season influenza vaccination rates during the COVID-19 pandemic. Influenza Other Respir Viruses. 2022 Nov;16(6):1141-1150. doi: 10.1111/irv.13041. Epub 2022 Sep 13.
Research topics and capabilities
Recent research projects include HIV treatment patterns and trends, vaccines uptake and effectiveness, hepatitis B and C burden, and characteristics of bacterial infections.
HIV treatment patterns and trends
- Lines of antiretroviral therapies (ARTs)
- ART initiation, switching and persistence
- Real-world ART first-line regimens relative to treatment guidelines
- ART adherence and burden of nonadherence
- Treatment failure and intolerability-associated events
- Quality of life among patients who switched due to side effects of ARTs
Hepatitis B and C
- Pill burden, adherence and discontinuation
- Comorbidities, concomitant medication use and potential drug-drug interactions
- Comparison of expected versus observed treatment duration
- Rate of sustained virologic response (SVR) following treatment
- Liver disease progression by genotype
- Screening rates and provider practice pattern changes over time
Vaccines
- Autism occurrence by MMR vaccine status, including linkage of infants to parents/siblings
- Incidence and burden of vaccine-preventable diseases: herpes zoster, pertussis, rotavirus, influenza, pneumococcal disease, invasive meningococcal disease
- Vaccine uptake and compliance
Bacterial infections
- Patterns of care and antibiotic treatment pathways
- Prevalence of antibiotic resistance
- Patient characteristics, clinical outcomes and economic outcomes by antibiotic class
- Post-surgical infection rate among patients with implantable devices