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Biomedical subjects

D M Patrick

Publications and source records attributed to D M Patrick.

30 records · Page 2Linked to original sources
PubMed1997

Needle exchange is not enough: lessons from the Vancouver injecting drug use study.

OBJECTIVE: To describe prevalence and incidence of HIV-1, hepatitis C virus (HCV) and risk behaviours in a prospective cohort of injecting drugs users (IDU). SETTING: Vancouver, which introduced a needle exchange programme (NEP) in 1988, and currently exchanges over 2 million needles per year. DESIGN: IDU who had injected illicit drugs within the previous month were recruited through street outreach. At baseline and semi-annually, subjects underwent serology for HIV-1 and HCV, and questionnaires on demographics, behaviours and NEP attendance were completed. Logistic regression analysis was used to identify determinants of HIV prevalence. RESULTS: Of 1006 IDU, 65% were men, and either white (65%) or Native (27%). Prevalence rates of HIV-1 and HCV were 23 and 88%, respectively. The majority (92%) had attended Vancouver's NEP, which was the most important syringe source for 78%. Identical proportions of known HIV-positive and HIV-negative IDU reported lending used syringes (40%). Of HIV-negative IDU, 39% borrowed used needles within the previous 6 months. Relative to HIV-negative IDU, HIV-positive IDU were more likely to frequently inject cocaine (72 versus 62%; P < 0.001). Independent predictors of HIV-positive serostatus were low education, unstable housing, commercial sex, borrowing needles, being an established IDU, injecting with others, and frequent NEP attendance. Based on 24 seroconversions among 257 follow-up visits, estimated HIV incidence was 18.6 per 100 person-years (95% confidence interval, 11.1-26.0). CONCLUSIONS: Despite having the largest NEP in North America, Vancouver has been experiencing an ongoing HIV epidemic. Whereas NEP are crucial for sterile syringe provision, they should be considered one component of a comprehensive programme including counselling, support and education.

Adolescent↗
PubMed1997

Determinants of HIV seroconversion in injection drug users during a period of rising prevalence in Vancouver.

To identify determinants of HIV seroconversion among injection drug users (IDUs) during a period of rising prevalence, a case-control investigation was conducted. Cases were IDUs with a new positive test after 1 January 1994, and a negative test within the prior 18 months. Controls required 2 negative tests during the same period. Subjects completed a questionnaire on demographic, psychosocial, and behavioural factors. Eighty-nine cases and 192 controls were similar with respect to gender, age, ethnicity and inter-test interval. Multivariate analyses of events during the inter-test interval showed borrowing syringes (adj. OR = 2.96; P < 0.006), unstable housing (adj. OR = 2.01; P = 0.03) and injecting > or = 4 times daily (adj. OR = 1.71; P = 0.06) to be independently associated with seroconversion. Protective associations were demonstrated for sex with opposite gender (adj. OR = 0.36; P = 0.001) and tetrahydrocannabinol use (adj. OR = 0.41; P = 0.001). There is a need to evaluate programmes dealing with addiction, housing and the social underpinnings of risk behaviours in this population.

Adult↗
PubMed1997

Social determinants predict needle-sharing behaviour among injection drug users in Vancouver, Canada.

Despite the fact that needle exchange was introduced in Vancouver as early as 1988, needle sharing remains common. An analysis was conducted to identify determinants of borrowing used needles among subjects participating in a case-control study. IDUs had a documented HIV seroconversion after 1 January, 1994 (n = 89), or repeatedly tested HIV-seronegative after this date (n = 192). Interviewer-administered questionnaires focused on drug use, sexual behaviours, source of needles and depression. Subjects were asked if they had "ever been forced to have sex" as a child, youth or adult. Logistic regression identified determinants of borrowing needles. After controlling for HIV serostatus, factors independently associated with borrowing were injecting > 4 times/day, polydrug use, and ever experiencing non-consensual sex (AOR = 3.4, 95% CI: 1.8, 6.5). Depression was associated with borrowing, although not independently so. Homosexual activity was independently associated with borrowing among males, whereas living with a sexual partner was an independent predictor for females. Access or barriers to clean needle use were not associated with borrowing. Social determinants, particularly a history of sexual abuse, are among the most significant predictors of needle borrowing among Vancouver's IDUs. Early identification of these factors should be a component of HIV prevention programmes.

Adult↗
PubMed1994

Unsatisfactory performance of the leukocyte esterase test of first voided urine for rapid diagnosis of urethritis.

BACKGROUND AND OBJECTIVES: The objective of this study was to determine the performance characteristics of a dipstick test for leukocyte esterase (LE), (Chemstrip 2LN, Boehringer Mannheim) in predicting the presence of urethritis and urethral pathogens in men presenting to a busy sexually transmitted disease clinic and to street outreach facilities. METHODS: Urethral swabs for polymorphonuclear (pmn) cell count, gonorrhoea culture and chlamydia enzyme immunoassay (EIA) as well as 15 ml of first voided urine (FVU) were collected from 737 symptomatic and 726 asymptomatic men. Gonorrhoea cultures and pmn counts were processed according to standard methods. Either Abbott Chlamydiazyme EIA (confirmed) or Syva Microtrak EIA (confirmed) test was employed to detect C trachomatis. The LE test was immediately dipped in FVU, read after 60-120 seconds by the clinician and considered positive if trace, 1+ or 2+. RESULTS: Microscopic evidence of urethritis (> or = = 4 pmn cells per 1000 x field) was found on urethral smear of 782 (53.5%) patients. Chlamydia, gonorrhoea or both were present in 104 (7.1%) patients. Performance characteristics of the LE test were as follows: (table below) CONCLUSION: The LE test did not have adequate sensitivity to be considered a reliable rapid diagnostic test for urethritis or urethral pathogens, particularly in the asymptomatic portion of this STD clinic population.

Adolescent↗
PubMed1990

Severe exacerbations of COPD and asthma. Incremental benefit of adding ipratropium to usual therapy.

Single dose studies have assessed the utility of ipratropium bromide alone or with beta agonists in the short- and long-term management of chronic obstructive lung disease and asthma. We performed a randomized, double-blind trial to assess the incremental benefit over 24 hours of adding ipratropium vs placebo to a standardized regimen of medications commonly used in the acute and subsequent hospital management of COPD and asthma. Sixty-eight subjects received nebulized salbutamol, intravenous methylprednisolone, intravenous aminophylline, and antibiotics and were randomized to receive either 80 micrograms of ipratropium or placebo via metered dose inhaler and spacing device with each salbutamol treatment (6 to 8 times per day). Among the 50 patients who completed the study, there were no significant differences between ipratropium and placebo groups with respect to baseline FEV1, FVC, and PaCO2. The improvement of FEV1 from baseline to 24 hours was 294 (SD = 568) ml in the ipratropium group vs 393 (SD = 622) ml in placebo group. Adjusting FEV1 by age, gender, and smoking did not significantly alter the findings. Those with an admission diagnosis of asthma showed larger 24 hour FEV1 responses (487 ml in ipratropium vs 801 ml in placebo) than those with COPD (149 ml ipratropium vs 102 ml in placebo). However, within these two strata, there were no significant differences in FEV1 improvement between ipratropium and placebo groups. This study suggests that if ipratropium is used in the initial emergency treatment of COPD or asthma, it could safely be discontinued by 24 hours in order to reduce the cost and complexity of therapy.

Administration, Inhalation↗
PubMedDate not supplied

Non-nominal HIV surveillance: preserving privacy while tracking an epidemic.

OBJECTIVE: To enhance HIV surveillance within a non-nominal provincial testing system. METHODS: Confirmatory HIV tests from a provincial laboratory were analyzed during 1995 and 1996. Enhancements included elimination of repeat positive tests for the same individual using automated matching of non-nominal identifiers and nurse call-back of health care providers, completion of missing information through call-back and connection of providers with resources for patient care. RESULTS: Forty-seven percent of 2,683 reactive HIV tests were identified as duplicates for the same individual, meaning that 1,401 people tested positive for the first time. From laboratory test data to enhanced unduplicated data after call-back, the proportion of tests for which risk and ethnic information was unknown dropped from 37% to 11% and from 64% to 18% respectively (p < 0.0001). CONCLUSIONS: Enhanced non-nominal surveillance for HIV is a practical means of marrying the needs of public health for epidemiological information and the rights of patients to privacy.

AIDS Serodiagnosis↗
PubMedDate not supplied

Public health and hepatitis C.

This paper reviews key public health aspects related to surveillance, transmission and primary prevention of hepatitis C. Hepatitis C is now a reportable disease in all Canadian provinces and territories. Although prevalence in Canada is estimated at under 1%, that associated with injection drug use (IDU) approaches 90%. The epidemiology of new HCV infections in Canada is now primarily defined by IDU behaviour, with annual incidence rates among new drug injectors exceeding 25%. HCV is less efficiently transmitted through other routes of exposure. An effective vaccine against HCV remains elusive. Some jurisdictions offer hepatitis A and hepatitis B vaccine to HCV-infected persons. An array of harm reduction strategies targeting IDU has been implemented but underdeployed across Canada, and has been ineffective to date in controlling the HCV epidemic. Public policy alternatives, such as legalization and regulation of injection drugs, are being debated. Improved HCV preventive strategies are urgently required and need careful evaluation.

Canada↗
PubMedDate not supplied

A cost-effectiveness analysis of pneumococcal vaccination in street-involved, HIV-infected patients.

BACKGROUND: Delivery of the pneumococcal vaccine (PCV) to street-involved, HIV patients in British Columbia is low due to poor compliance. Since the use of PCV is expected to reduce morbidity and mortality, it may be more cost-effective to provide the vaccine directly to clinics. METHODS: Three strategies were compared for a cohort of 5000 patients: 1) administering PCV at the clinics; 2) giving a prescription for PCV and expecting patients to fill it at a pharmacy and return for administration; and 3) no administration of vaccine. Decision analysis was utilized to map the costs and outcomes of the patients over 5 years and conduct an incremental cost-effectiveness analysis from the perspective of the Ministry of Health. RESULTS: The average cost per patient was the lowest in Strategy 1 ($549) compared to Strategy 2 ($702) and Strategy 3 ($714). For the cohort, Strategy 1 prevented 269 and 299 additional cases of pneumococcal disease and resulted in a cost savings of $535,000 and $595,000 in direct medical costs when compared to Strategies 2 and 3, respectively. The model was robust to extensive sensitivity analyses. CONCLUSIONS: The Ministry of Health should supply PCV to clinics involved in the care of street-involved HIV patients as this is the most cost-effective strategy.

AIDS-Related Opportunistic Infections↗