The impact of wait time on patient outcomes in knee and hip replacement surgery: a scoping review protocol

BACKGROUND

Total hip and total knee replacement surgery are in high demand, leading to long wait times for many patients. While on the waiting list, patients may experience worsening pain, reduced mobility, and deteriorating health. Given that long wait times are common for lower joint replacement surgery, it is important to understand how patient health changes during the wait period and whether this impacts patient outcomes after surgery. The aim of this scoping review will be to identify and describe the evidence regarding the impact of wait time on patient outcomes for patients who undergo total knee and total hip replacement surgery.

METHODS

This scoping review was designed with guidance from the Joanna Briggs Institute Manual for Evidence Synthesis, and results will be reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews. EMBASE, Medline, PubMed, Scopus, CINAHL, and Cochrane electronic databases will be searched for English language articles published after 1999. Studies of adult patients with osteoarthritis undergoing primary knee or hip replacement surgery, which measure patient outcomes over the wait period for surgery, will be included. Two independent reviewers will screen titles and abstracts followed by full article review. Data will be extracted by two reviewers using a standardized form. Outcomes assessed during the wait period will be identified and described in tables. Factors associated with changes in health status during the wait period will be qualitatively described.

DISCUSSION

This review will map the evidence regarding wait times for lower extremity joint replacement surgery. Better understanding of how the impact of wait times on patient health status is measured over the perioperative period will inform future research on wait times.

SCOPING REVIEW REGISTRATION

Registered with Open Science Framework, Feb 14, 2021 DOI: https://doi.org/10.17605/OSF.IO/MV4FS.

Assessing the epidemiological and economic impact of alternative vaccination strategies: a modeling study

Purpose

Given limited supplies of vaccines, having information on the costs, and associated health and economic impacts, is important for the development of optimal vaccination strategies. This study explores the epidemiological and economic impact, in terms of the value of lost production, of four vaccination strategies – fixed-dose interval (M1), prioritization of the first dose (M2), screen and forego vaccine for those with COVID-19 infection history (M3), and prioritization of the first dose along with screen and forego vaccine for those with COVID-19 infection history(M4), under constraints limiting the daily vaccine supply.

Methods & Materials

Using mathematical and statistical modelling, we quantified the number quarantined, hospitalization days, vaccine doses saved, and deaths averted, and production losses, for each strategy, in comparison to M1. The model parameters and initial conditions were based on Canadian data, and the simulation ran over 365 days starting from June 1, 2021. Sensitivity analyses explored how each strategy changes with different conditions of daily vaccine supply, the initial proportion recovered from COVID-19 infection, and initial coverage of the first dose.

Results

Strategy M2 results in a reduction of 67,130,775 doses of vaccine administered, 20 lives saved, and a reduction of $3.8 billion of lost production in comparison to M1. M3 does not save any vaccine dose administered, but results in 5 lives saved, and a reduction of $575,149 in lost production in comparison to strategy M1. Due to the large proportion of the Canadian population who have already received a first vaccine dose, no screening actually occurs under scenario M3 and the daily vaccine supply was used entirely to provide second doses. While M2 is the dominant strategy under the current Canadian setting, sensitivity analyses revealed that M3 dominates when the vaccine supply increased or when the initial recovered proportion from COVID-19 was large enough.

Conclusion

The findings quantify the potential benefits of alternative vaccination strategies that can save lives and costs. Our study findings can help policymakers identify the optimal COVID-19 vaccination strategy and our study framework can be adapted to other settings.

Evaluation of miR-216a and miR-217 as Potential Biomarkers of Acute Exocrine Pancreatic Toxicity in Rats

Detecting and monitoring exocrine pancreatic damage during nonclinical and clinical testing is challenging because classical biomarkers amylase and lipase have limited sensitivity and specificity. Novel biomarkers for drug-induced pancreatic injury are needed to improve safety assessment and reduce late-stage attrition rates. In a series of studies, miR-216a and miR-217 were evaluated as potential biomarkers of acute exocrine pancreatic toxicity in rats. Our results revealed that miR-216a and miR-217 were almost exclusively expressed in rat pancreas and that circulating miR-216a and miR-217 were significantly increased in rats following administration of established exocrine pancreatic toxicants caerulein (CL) and 1-cyano-2-hydroxy-3-butene (CHB) as well as in rats administered a proprietary molecule known to primarily affect the exocrine pancreas. Conversely, neither microRNA was increased in rats administered a proprietary molecule known to cause a lesion at the pancreatic endocrine–exocrine interface (EEI) or in rats administered an established renal toxicant. Compared with amylase and lipase, increases in miR-216a and miR-217 were of greater magnitude, persisted longer, and/or correlated better with microscopic findings within the exocrine pancreas. Our findings demonstrate that in rats, miR-216a and miR-217 are sensitive and specific biomarkers of acute exocrine pancreatic toxicity that may add value to the measurement of classical pancreatic biomarkers.

Identification and Evaluation of Novel MicroRNA Biomarkers in Plasma and Feces Associated with Drug-induced Intestinal Toxicity

Gastrointestinal toxicity is dose limiting with many therapeutic and anticancer agents. Real-time, noninvasive detection of markers of toxicity in biofluids is advantageous. Ongoing research has revealed microRNAs as potential diagnostic and predictive biomarkers for the detection of select organ toxicities. To study the potential utility of microRNA biomarkers of intestinal injury in a preclinical toxicology species, we evaluated 3 rodent models of drug-induced intestinal toxicity, each with a distinct mechanism of toxicity. MiR-215 and miR-194 were identified as putative intestinal toxicity biomarkers. Both were evaluated in plasma and feces and compared to plasma citrulline, an established intestinal injury biomarker. Following intestinal toxicant dosing, microRNA changes in feces and plasma were detected noninvasively and correlated with histologic evidence of intestinal injury. Fecal miR-215 and miR-194 levels increased, and plasma miR-215 decreased in a dose- and time-dependent manner. Dose-dependent decreases in plasma miR-215 levels also preceded and correlated positively with plasma citrulline modulation, suggesting miR-215 is a more sensitive biomarker. Moreover, during the drug-free recovery phase, plasma miR-215 returned to predose levels, supporting a corresponding recovery of histologic lesions. Despite limitations, this study provides preliminary evidence that select microRNAs have the potential to act as noninvasive, sensitive, and quantitative biomarkers of intestinal injury.

Comparing surgical trays with redundant instruments with trays with reduced instruments: a cost analysis

BACKGROUND

When prearranged standard surgical trays contain instruments that are repeatedly unused, the redundancy can result in unnecessary health care costs. Our objective was to estimate potential savings by performing an economic evaluation comparing the cost of surgical trays with redundant instruments with surgical trays with reduced instruments ("reduced trays").

METHODS

We performed a cost-analysis from the hospital perspective over a 1-year period. Using a mathematical model, we compared the direct costs of trays containing redundant instruments to reduced trays for 5 otolaryngology procedures. We incorporated data from several sources including local hospital data on surgical volume, the number of instruments on redundant and reduced trays, wages of personnel and time required to pack instruments. From the literature, we incorporated instrument depreciation costs and the time required to decontaminate an instrument. We performed 1-way sensitivity analyses on all variables, including surgical volume. Costs were estimated in 2013 Canadian dollars.

RESULTS

The cost of redundant trays was $21 806 and the cost of reduced trays was $8803, for a 1-year cost saving of $13 003. In sensitivity analyses, cost savings ranged from $3262 to $21 395, based on the surgical volume at the institution. Variation in surgical volume resulted in a wider range of estimates, with a minimum of $3253 for low-volume to a maximum of $52 012 for high-volume institutions.

INTERPRETATION

Our study suggests moderate savings may be achieved by reducing surgical tray redundancy and, if applied to other surgical specialties, may result in savings to Canadian health care systems.

Antitumor Efficacy of the Dual PI3K/mTOR Inhibitor PF-04691502 in a Human Xenograft Tumor Model Derived from Colorectal Cancer Stem Cells Harboring a PIK3CA Mutation

PIK3CA (phosphoinositide-3-kinase, catalytic, alpha polypeptide) mutations can help predict the antitumor activity of phosphatidylinositol-3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway inhibitors in both preclinical and clinical settings. In light of the recent discovery of tumor-initiating cancer stem cells (CSCs) in various tumor types, we developed an in vitro CSC model from xenograft tumors established in mice from a colorectal cancer patient tumor in which the CD133+/EpCAM+ population represented tumor-initiating cells. CD133+/EpCAM+ CSCs were enriched under stem cell culture conditions and formed 3-dimensional tumor spheroids. Tumor spheroid cells exhibited CSC properties, including the capability for differentiation and self-renewal, higher tumorigenic potential and chemo-resistance. Genetic analysis using an OncoCarta™ panel revealed a PIK3CA (H1047R) mutation in these cells. Using a dual PI3K/mTOR inhibitor, PF-04691502, we then showed that blockage of the PI3K/mTOR pathway inhibited the in vitro proliferation of CSCs and in vivo xenograft tumor growth with manageable toxicity. Tumor growth inhibition in mice was accompanied by a significant reduction of phosphorylated Akt (pAKT) (S473), a well-established surrogate biomarker of PI3K/mTOR signaling pathway inhibition. Collectively, our data suggest that PF-04691502 exhibits potent anticancer activity in colorectal cancer by targeting both PIK3CA (H1047R) mutant CSCs and their derivatives. These results may assist in the clinical development of PF-04691502 for the treatment of a subpopulation of colorectal cancer patients with poor outcomes.

Synergistic effect of the γ-secretase inhibitor PF-03084014 and docetaxel in breast cancer models

Notch signaling mediates breast cancer cell survival and chemoresistance. In this report, we aimed to evaluate the antitumor efficacy of PF-03084014 in combination with docetaxel in triple-negative breast cancer models. The mechanism of action was investigated. PF-03084014 significantly enhanced the antitumor activity of docetaxel in multiple xenograft models including HCC1599, MDA-MB-231Luc, and AA1077. Docetaxel activated the Notch pathway by increasing the cleaved Notch1 intracellular domain and suppressing the endogenous Notch inhibitor NUMB. PF-03084014 used in combination with docetaxel reversed these effects and demonstrated early-stage synergistic apoptosis. Docetaxel elicited chemoresistance by elevating cytokine release and expression of survivin and induced an endothelial mesenchymal transition (EMT) phenotype by increasing the expressions of Snail, Slug, and N-cadherin. When reimplanted, the docetaxel-residual cells not only became much more tumorigenic, as evidenced by a higher fraction of tumor-initiating cells (TICs), but also showed higher metastatic potential compared with nontreated cells, leading to significantly shortened survival. In contrast, PF-03084014 was able to suppress expression of survivin and MCL1, reduce ABCB1 and ABCC2, upregulate BIM, reverse the EMT phenotype, and diminish the TICs. Additionally, the changes to the ALDH(+) and CD133(+)/CD44(+) subpopulations following therapy corresponded with the TIC self-renewal assay outcome. In summary, PF-03084014 demonstrated synergistic effects with docetaxel through multiple mechanisms. This work provides a strong preclinical rationale for the clinical utility of PF-03084014 to improve taxane therapy.

Prostate effect in dogs with the aldosterone receptor blocker eplerenone

Eplerenone (Inspra) is an aldosterone receptor antagonist approved for the treatment of hypertension and heart failure after a myocardial infarction. In vitro receptor binding and transactivation studies showed eplerenone had high selectivity for the mineralocorticoid receptor over other steroid receptors (glucocorticoid, androgen, and progesterone). The most sensitive off-target effect of orally administered eplerenone preclinically was prostate atrophy in dogs. Dose-related prostate atrophy was observed at eplerenone dosages ≥15 mg/kg/day for 13 weeks or longer. The no observed adverse effect level (NOAEL) for the prostate effect in dogs was 5 mg/kg/day. The maximal effect was seen by 13 weeks and the atrophy was reversible even after 1 year of daily treatment. An additional study demonstrated dogs with eplerenone-induced prostate atrophy (confirmed by intrarectal ultrasound) had slightly decreased semen volume but no compound-related effects on libido, semen protein content, sperm motility, daily sperm production, or epididymal sperm transit time. Four possible mechanisms for prostate effect were investigated: (1) inhibition of testosterone synthesis and secretion; (2) inhibition of 5α-reductase, the enzyme within the prostate that converts testosterone into the more active growth factor dihydrotestosterone (DHT); (3) competitive antagonism of the androgen receptor; and (4) inhibition of 5α-reductase or competitive antagonism of the androgen receptor by aldosterone, which increased in dogs treated with eplerenone. Data from these studies supported blockade of androgen receptors at suprapharmacological concentrations of eplerenone. Another mineralocorticoid blocker, spironolactone, had greater antiandrogenic activity than eplerenone both in vivo and in vitro, and it has well known clinically significant antiandrogenic effects in humans, whereas eplerenone does not.

Comparison of 3 Kidney Injury Multiplex Panels in Rats

Kidney injury biomarkers have been utilized by pharmaceutical companies as a means to assess the potential of candidate drugs to induce nephrotoxicity. Multiple platforms and assay methods exist, but the comparison of these methods has not been described. Millipore’s Kidney Toxicity panel, EMD/Novagen’s Widescreen Kidney Toxicity panel, and Meso Scales Kidney Injury panel were selected based on published information. Kidney injury molecule 1, cystatin C, clusterin, and osteopontin were the 4 biomarkers common among all kits tested and the focus of this study. Rats were treated with a low and high dose of para-aminophenol, a known nephrotoxicant, and urine samples were collected and analyzed on the Bio-Plex 200 or MSD’s Sector Imager 6000, according to manufacturers specifications. Comparatively, of the 3 kits, Millipore was the most consistent in detecting elevations of 3 out of the 4 biomarkers at both dose levels and indicated time points.

Limitations of an ocular surface inflammatory biomarker in impression cytology specimens

CONTEXT

A number of ocular conditions, such as dry eye, are associated with inflammation on the surface of the eye leading to irritation and ocular pain. Many drugs such as chemotherapeutics, beta blockers, angiotensin-converting enzymes and so forth also cause dry eye but currently there are no validated ocular surface biomarkers available.

OBJECTIVE

We evaluated sample stability, assay sensitivity, reproducibility and overall performance of impression cytology (IC) utilizing the cellular surface biomarker human leukocyte antigen DR-1 (HLA-DR) as an ocular surface inflammatory biomarker by flow cytometry in a fit-for-purpose validation study. Additionally, subjects classified as normal or having various degrees of dry eye were evaluated to determine if HLA-DR could demonstrate a clear separation between normal and dry eye samples.

RESULTS

The assay demonstrated high dynamic range detecting a broad range of fluorescent intensities in healthy donors. Additionally, inter, intra and stability assay results demonstrated strong concordance and low variability. Overall CV% for both assays were less than 25% for all measured parameters. However, high variability was observed for donor samples assayed beyond day 10 post IC sample collection (4.2-110.8 CV%).

DISCUSSION

HLA-DR expression demonstrated a progressive increase in patients with mild to severe levels of dry eye disease providing sufficient evidence it is sensitive enough to monitor inflammatory effects of dry eye when coupled with additional biomarkers and/or methodologies such as cytokine analysis or ICAM-1. This biomarker can be used to monitor ocular surface disorders in patients and to evaluate potential treatment options during drug development. Although our results demonstrate this methodology is reproducible for routine evaluation, limitations around sample integrity exist.

CONCLUSION

The ocular cell surface inflammatory biomarker, HLA-DR coupled with impression cytology is a simple non-invasive robust, specific and reproducible assay that can be utilized to measure inflammatory infiltrates on the surface of the eye in IC samples less than 10-days old.

Sunitinib, a receptor tyrosine kinase inhibitor, increases blood pressure in rats without associated changes in cardiac structure and function

BACKGROUND

Sunitinib, a multi-tyrosine kinase inhibitor has demonstrated clinical activity in advanced renal cell carcinoma and imatinib-resistant/intolerant gastrointestinal stromal tumor. It has been associated with manageable hypertension and other unique toxicities.

AIMS

Two nonclinical studies were conducted to determine if sunitinib has direct/indirect effects on cardiac structure/function that may be related to hypertension at clinically relevant exposures.

MATERIALS & METHODS

Rats received once-daily vehicle or sunitinib 1 or 10 mg/kg/day (n = 10/group) orally for 4 weeks, followed by 2 weeks off treatment then a 2-week rechallenge. Blood pressure (BP) and heart rate (HR) were continuously acquired and echocardiograms were obtained weekly. Effects of sunitinib and its metabolite (0.003-0.3 μM) were also evaluated in guinea pig isolated Langendorff-perfused hearts (n = 4-6 hearts/group).

RESULTS

Sunitinib 10 mg/kg/day produced significant (P < 0.05) hemodynamic changes: 24 h average BP increased during initial dosing/rechallenge, with rebound hypotension during the off-treatment period; 24 h average HR increased during the off-treatment period, and decreased during rechallenge; no changes in cardiac structure/function were observed. In guinea pig isolated hearts, neither sunitinib nor its metabolite had direct effects on contractility, HR or left ventricular pressure.

DISCUSSION & CONCLUSION

These studies demonstrate that sunitinib/metabolite had no direct effects on cardiac function ex vivo, and that therapeutically relevant concentrations of sunitinib dosed on a "clinical schedule" increased BP in rats without adverse changes in cardiac structure/function.

Abstract 1681: Paradoxical induction of epithelial hyperplasia by a selective raf inhibitor

Raf kinases (A-Raf, B-Raf, C-Raf) link Ras activation to MEK/ERK pathway activation, and are part of the key MAPK signaling pathway that controls cellular functions such as cell proliferation, migration, differentiation, and survival. Activating mutations in B-Raf occurs in a variety of cancers and inhibition of these signaling proteins in the pathway, therefore, represents a therapeutic targeting strategy for diverse cancers.

We developed PF-04880594, an ATP-competitive and reversible inhibitor of B-Raf. To assess safety prior to initiation of clinical trials, repeat dose toxicity studies were performed in the rat and dog. Animals were treated orally at 0, 25, 75, 300→150 mg/kg/day in the rat or 0, 0.5, 6, 15→12 mg/kg/day in the dog for 30 days followed by a 30-day treatment-free period to assess recovery or delayed toxicity. Plasma concentrations of the B-Raf inhibitor were measured on Day 1 and at the end of the dosing phase of the study. Body weight and food consumption were measured at regular intervals and clinical signs were recorded daily. In the rat, dose-related clinical signs, occurring in the skin at ≥ 25 mg/kg included dry skin and/or edema in the paws, erythema and desquamation of tail skin &gt; 75 mg/kg, and erythema of the ear at 300→150 mg/kg. In the dog, clinical signs observed at ≥ 6 mg/kg included desquamation and alopecia of the skin involving the ear, head, eyebrow, muzzle, thorax, lips, nose, scrotum or forepaw; and edema of the ear, muzzle, head, forepaw, hindpaw or scrotum. Erythema was observed at all dose levels on the muzzle, ear or head during life. In both species, these clinical signs correlated microscopically with epithelial hyperplasia in these affected tissues. Hyperplasia of the stratified epithelium of the tongue and esophagus occurred in both species, In the rat, epithelial hyperplasia was additionally observed in the urinary bladder and nonglandular stomach and dose-related proliferation of woven bone was observed primarily on endocortical surfaces in the proximal tibia and /or distal femur. Clinical pathology revealed an inflammatory response indicated by increased fibrinogen and neutrophil counts in dogs at ≥ 6 mg/kg (males &gt; females) and in rats at ≥ 75 mg/kg. At the end of the recovery period, the inflammatory response and the woven bone changes were not evident, but epithelial hyperplasia was only partly resolved. A no-observed-effect-level was not identified in either study due to the epithelial hyperplasia. At low doses, margins of exposure were over 10-fold in the rat and 0.03-fold in the dog of projected clinically efficacious plasma concentration in humans.

These studies indicate epithelial hyperplasia is paradoxically induced by this selective B-Raf inhibitor. The occurrence of this change in the rodent and canine suggests that this effect could develop in other mammalian species. Combination studies to test the effects of Raf and MEK inhibition on hyperplasia are currently being investigated.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1681.

Abstract 4483: Establishing patient-derived colorectal cancer stem cell models with a PIK3CA mutation for the development of inhibitory drugs as targeted therapies

Emerging evidences suggest that cancer stem cells (CSC) may be critically responsible for tumor initiation, progression, metastasis, and drug resistance. It becomes important to ask whether anti-cancer agents are able to target the tumor-initiating subpopulation in relevant CSC models. In this study, we first established xenograft tumors in NOD/SCID mice from a colorectal cancer patient specimen and demonstrated that CD133/EpCAM-expressing CSC population was highly tumorigenic. We then sought to propagate the CSC population under a serum-free condition. In culture, the tumor cells formed non-adherent, 3-dimensional spheroids, a fraction of which retained expression of the CSC markers. When exposed to a serum-containing medium, tumor spheroid cells differentiated into epithelial-like adherent cells with an increase in cell proliferation rate. In comparison with the differentiated progeny, tumor spheroid cells exhibited resistance to the standard-of-care agent oxaliplatin and, in limiting dilution assays in mice, displayed substantially higher tumorigenic potential. In contrast to the tumors originated from the differentiated cells, tumor spheroid cell-derived tumors recapitulated not only the CSC frequency marked by CD133/EpCAM expression, but also the histological characters of the original tumor. Similarly, only were the fragments of spheroid cell-derived xenograft tumors capable of regenerating highly proliferative tumors in secondary transplantation. Thus, the tumor spheroid culture is indeed enriched of drug resistant, self-renewing, and tumor-initiating CSC populations. Mutation profiling of frequently mutated oncogenes using Sequenom OncoCarta™ panel identified a mutation in the kinase domain of PIK3CA (H1047R) in the cultured CSCs. This mutation has been reported present in a large number of colon cancer patients and likely functions as an oncogene (Samuels et al., Science 304:554; 2004). We further demonstrated that a dual mammalian target of rapamycin (mTOR)/phosphoinositide 3-kinase (PI3K) inhibitor (PF-04691502) exhibited a more potent effect on inhibition of in vitro proliferation of the mutated CSCs compared to the chemotoxic agent oxaliplatin. Collectively, our findings suggest that CSC models provide a novel avenue to drug sensitivity and efficacy studies. The well-characterized CSC model systems may assist in the development of more effective therapy against the subpopulation of tumors driven by the CSCs bearing specific mutations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4483.

Assay development and validation of inflammatory markers in impression cytology specimens (144.19)

The principle of Impression Cytology (IC) utilizes a non-invasive technique to remove superficial layers of the ocular surface. The application of a filter to the surface of the bulbar conjunctiva allows for repeated collection of superficial cells for the analysis of ocular surface disorders. Evidence suggests expression of the HLA-DR antigen on the surface of conjunctival epithelial cells is associated with allergic conjunctivitis and dry eye syndrome. Performance characteristics of HLA-DR was evaluated through intra, inter and stability assays. Evaluation of the reproducibility and overall performance of the novel methodology would be useful in understanding the tolerance level of the assay. Utilizing established techniques, IC specimens were obtained from 12 donors and assayed over multiple days and timepoints. Conjunctival epithelial cells were extracted and assayed based on differential immunostaining of both conjunctival epithelial cells and leukocytes. The reproducibility across donors over time was consistent, demonstrating conjunctival cells maintained their integrity of cell surface expression of HLA-DR. In conclusion, the studies met all validation criteria, and support the utilization of HLA-DR inflammatory measurements in impression cytology specimens. Utilization of a flow cytometric platform to examine the expression of HLA-DR antigen may help predict clinical outcome, evaluate disease progression, and monitor the effects of treatment.

Treatment of hepatitis C infection for current or former substance abusers in a community setting

Substance abusers account for the largest number of hepatitis C infected cases in developed countries. We describe a care model for treating current or former substance abusers with antiviral therapy for hepatitis C virus (HCV) infection. The care model involved hepatitis nurses, a psychologist, infectious disease specialist and primary care physicians. Clients met selection criteria including regular attendance at clinic appointments and social stability. Use of alcohol and illicit substances was monitored with urine toxicology screens. The association between substance use, rates of completion of therapy and rates of response were assessed using multivariable regression analyses. A total of 109 clients (75 with genotype 1/4 and 34 with genotype 2/3) received at least one injection with pegylated interferon between November 2002 and January 2006. Treatment completion rates of 61 and 74% were achieved for genotypes 1/4 and 2/3, respectively. Treatment response rates in an intention to treat analysis were 51% for genotypes 1/4 and 68% for genotypes 2/3. A positive urine toxicology screen indicating use of illicit substances 6 months prior to initiating therapy was significantly associated with lower rates of treatment completion but not lower rates of sustained virological response. A positive urine screen indicating use of alcohol prior to therapy was significantly associated with lower rates of completion and lower rates of response. Rates of completion and response are comparable to non-substance abusing populations. Antiviral therapy for HCV infection can be successful within the context of ongoing care for substance abuse for carefully selected patients.