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Clinically Significant Drug Interactions Among Human Immunodeficiency Virus–Positive Patients on Antiretroviral Therapy in an Outpatient Setting

Monday, Lea M. MD, PharmD*; Veltman, Jennifer MD

Infectious Diseases in Clinical Practice: September 2018 - Volume 26 - Issue 5 - p 279–282
doi: 10.1097/IPC.0000000000000636
Original Articles

Human immunodeficiency virus (HIV) treatment is complicated by antiretrovirals prone to clinically significant drug interactions (CSDIs). Objectives were to examine relationships of patient and medication characteristics and provider training level with CSDIs in an outpatient HIV clinic. A clinical pharmacist reviewed medication lists of randomly selected adult HIV-positive patients on antiretrovirals for accuracy and presence of a CSDI, defined as grade C, D, or X using Lexicomp software. Characteristics were compared between patients with and without CSDIs by χ2 tests for categorical variables and t tests for continuous variables. Associations between these parameters and CSDIs (presence vs absence) were evaluated by logistic regression. Associations between provider type (infectious disease physician [IDMD], infectious disease fellow [Fellow], and nurse practitioner [NP]) and number of CSDIs per patient, and provider response to being informed of a CSDI were analyzed by χ2 tests.

Of 107 records reviewed, 405 CSDIs were identified in 83 (76%) patient records. Clinically significant drug interaction presence was associated with older age, increased medications, protease inhibitor-based regimen, and medication list inaccuracies. Patients with and without CSDIs did not differ in sex, race, HIV viral load, or nonnucleoside reverse-transcriptase inhibitor regimen. Older age (odds ratio [95% confidence interval], 3.53 [1.21–11.64]) and a protease inhibitor-based regimen (odds ratio [95% confidence interval], 8.49 [2.18–46.07]) were associated with having a CSDI. Fellows were more likely to report being unaware of CSDIs than IDMDs and NPs and to request additional information versus IDMDs and NPs. These findings suggest that providers may benefit from involving a pharmacist to identify and educate about CSDIs.

Clinically significant drug interactions (CSDIs) were found in 76% of HIV-positive outpatients. Practitioners did not identify 78% of these CSDIs. Interactions were associated with older patients, increased medications, PI-based regimen, and medication list inaccuracies. Infectious disease fellows were more likely to report being unaware of significant drug interactions and request more information from the pharmacist when compared to attending physicians or nurse practitioners.

From the *Department of Internal Medicine; and

Tolan Park Medical Office Building, Detroit, MI.

Correspondence to: Lea M. Monday, MD, PharmD, Department of Internal Medicine, 4201 St Antoine St, Suite 2E, Detroit, MI 48201. E-mail:

Funding for this study was provided to L.M.M. by Infectious Disease Society of America Medical Scholars Award Grant (US $2000). The authors have no conflicts of interest to disclose.

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