Time trends in social contacts before and during the COVID-19 pandemic: the CONNECT study.

BACKGROUND: Since the beginning of the COVID-19 pandemic, many countries, including Canada, have adopted unprecedented physical distancing measures such as closure of schools and non-essential businesses, and restrictions on gatherings and household visits. We described time trends in social contacts for the pre-pandemic and pandemic periods in Quebec, Canada. METHODS: CONNECT is a population-based study of social contacts conducted shortly before (2018/2019) and during the COVID-19 pandemic (April 2020 - February 2021), using the same methodology for both periods. We recruited participants by random digit dialing and collected data by self-administered web-based questionnaires. Questionnaires documented socio-demographic characteristics and social contacts for two assigned days. A contact was defined as a two-way conversation at a distance ≤ 2 m or as a physical contact, irrespective of masking. We used weighted generalized linear models with a Poisson distribution and robust variance (taking possible overdispersion into account) to compare the mean number of social contacts over time and by socio-demographic characteristics. RESULTS: A total of 1291 and 5516 Quebecers completed the study before and during the pandemic, respectively. Contacts significantly decreased from a mean of 8 contacts/day prior to the pandemic to 3 contacts/day during the spring 2020 lockdown. Contacts remained lower than the pre-COVID period thereafter (lowest = 3 contacts/day during the Christmas 2020/2021 holidays, highest = 5 in September 2020). Contacts at work, during leisure activities/in other locations, and at home with visitors showed the greatest decreases since the beginning of the pandemic. All sociodemographic subgroups showed significant decreases of contacts since the beginning of the pandemic. The mixing matrices illustrated the impact of public health measures (e.g. school closure, gathering restrictions) with fewer contacts between children/teenagers and fewer contacts outside of the three main diagonals of contacts between same-age partners/siblings and between children and their parents. CONCLUSION: Physical distancing measures in Quebec significantly decreased social contacts, which most likely mitigated the spread of COVID-19.

Appropriateness of Ticagrelor Use at Initiation: A Population-Based Cohort Study.

PURPOSE: Ticagrelor is recommended following an acute coronary syndrome if used appropriately. Its use has not yet been well described in the context of ambulatory clinical practice. The objective of this study was to assess the proportion of ticagrelor new users who initiated this medication appropriately and explore associated factors. METHODS: A retrospective population-based inception cohort study was conducted using Quebec administrative databases. The study population included all Quebec residents aged ≥18 years who had a first ticagrelor prescription claim between 1 January, 2012, and 31 March, 2015, and had been continuously eligible in the Quebec public drug plan during the 365 days preceding the first ticagrelor claim. The initial ticagrelor prescription was considered appropriate if:1) it met the indication for use criterion, 2) the prescribed daily dose was 90 mg twice a day, and 3) there was a concomitant use of acetylsalicylic acid (ASA) 80-81 mg daily. Factors potentially associated with the ticagrelor appropriateness of use were included in a logistic log-binomial regression model. RESULTS: A total of 7,073 patients were included in the study, 6,013 (85.0%) had an appropriate indication, 6,895 (97.5%) were prescribed ticagrelor 90 mg twice a day, and 6,385 (90.3%) had a concomitant prescription of ASA. A total of 5,371 (75.9%) patients were prescribed ticagrelor in accordance with all criteria. Twelve factors were associated with prescription appropriateness. CONCLUSIONS: A large majority of patients initiated ticagrelor appropriately. Further improvement in appropriateness may come at targeting indication for use.

Lipid Selectivity, Orientation, and Extent of Membrane Binding of Nonacylated RP2.

Retinitis pigmentosa 2 (RP2) is an ubiquitary protein of 350 residues. The N-terminus of RP2 contains putative sites of myristoylation and palmitoylation. The dually acylated protein is predominantly localized to the plasma membrane. However, clinically occurring substitution mutations of RP2 in photoreceptors lead to the expression of a nonacylated protein, which was shown to be misrouted to intracellular organelles using different cell lines. However, the parameters responsible for the modulation of the membrane binding of nonacylated RP2 (naRP2) are still largely unknown. The maximal insertion pressure of naRP2 has thus been determined after its injection into the subphase underneath monolayers of phospholipids, which are typical of photoreceptor membranes. These data demonstrated that naRP2 shows a preferential binding to saturated phospholipid monolayers. Moreover, polarization modulation infrared reflection absorption spectroscopy has allowed comparison of the secondary structure of this protein in solution and upon binding to phospholipid monolayers. In addition, simulations of these spectra have allowed to determine that the ß-helix of naRP2 has an orientation of 60° with respect to the normal, which remains unchanged regardless of the type of phospholipid. Finally, ellipsometric measurements of naRP2 demonstrated that its particular affinity for saturated phospholipids can be explained by its larger extent of insertion in this phospholipid monolayer compared to that in polyunsaturated phospholipid monolayers.

Testing problem solving in turkey vultures (Cathartes aura) using the string-pulling test.

To examine problem solving in turkey vultures (Cathartes aura), six captive vultures were presented with a string-pulling task, which involved drawing a string up to access food. This test has been used to assess cognition in many bird species. A small piece of meat suspended by a string was attached to a perch. Two birds solved the problem without apparent trial-and-error learning; a third bird solved the problem after observing a successful bird, suggesting that this individual learned from the other vulture. The remaining birds failed to complete the task. The successful birds significantly reduced the time needed to solve the task from early trials compared to late trials, suggesting that they had learned to solve the problem and improved their technique. The successful vultures solved the problem in a novel way: they pulled the string through their beak with their tongue, and may have gathered the string in their crop until the food was in reach. In contrast, ravens, parrots and finches use a stepwise process; they pull the string up, tuck it under foot, and reach down to pull up another length. As scavengers, turkey vultures use their beak for tearing and ripping at carcasses, but possess large, flat, webbed feet that are ill-suited to pulling or grasping. The ability to solve this problem and the novel approach used by the turkey vultures in this study may be a result of the unique evolutionary pressures imposed on this scavenging species.

Sexual risk factors associated with intimate partner violence against women in Rwanda: a couples-based analysis.

The goal of this study was to measure the prevalence of intimate partner violence (IPV) against women and to examine the independent association of sexual risk factors of women and their husbands/partners with IPV. We used data from 2,169 couples from the 2005 Rwanda Demographic and Health Survey. Face-to-face interviews were conducted, and multiple logistic regression was used to calculate adjusted odds ratios (AOR) and 95% confidence intervals (CI). A total of 560 (29.2%), 415 (22.2%), and 233 (12.4%) women reported any physical, psychological, or sexual IPV, respectively. History of genital ulcer in women was significantly associated with psychological IPV (AOR: 2.77; 95% CI: 1.67-4.59), whereas history of genital ulcer reported by husbands/partners was significantly associated with sexual IPV (AOR 2.80, 95% CI: 1.08-7.29). The number of lifetime sexual partners of husbands was positively associated with increasing odds of their wives being exposed to psychological IPV (p = 0.025) and physical IPV (p = .017). In a representative sample of couples, husbands/partners' sexual risk factors were associated with IPV reported by their wives. Genital ulcer appeared to be a risk marker for the presence of IPV victimization/perpetration.

Periodical antibiotic treatment for the control of gonococcal and chlamydial infections among sex workers in Benin and Ghana: a cluster-randomized placebo-controlled trial.

BACKGROUND: In resource-poor settings, control of Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) among female sex workers (FSWs) is difficult. We sought to determine whether periodical antibiotic treatment (PAT) might be effective in controlling these infections among West African FSWs. Secondary objectives were to determine the impact of PAT on human immunodeficiency virus (HIV) incidence among FSWs and on NG/CT prevalence among their clients. METHODS: Cluster-randomized, double-blind, placebo-controlled trial among FSW communities in Benin and Ghana. Within each of 9 pairs of clusters of FSW communities, one was allocated to receive, during 9 months, a monthly antibiotic (alternatively ciprofloxacin or azithromycin, n = 296 FSWs) and the other a placebo (n = 340 FSWs). Prevalence of NG/CT infections was measured at 3-month intervals using the polymerase chain reaction. HIV status was determined at the beginning and at the end of the study. RESULTS: After adjusting for age, HIV status, duration of prostitution, price per intercourse and condom use, and accounting for prevalence at enrollment and cluster-pairing effect, prevalence ratios (intervention vs. placebo) of NG infection were 0.77 (P = NS), 1.07 (P = NS), and 0.49 (P = 0.05) at the first, second, and third follow-up visits, respectively. PAT neither reduced significantly CT prevalence or HIV incidence among FSWs nor NG/CT prevalence among their clients. CONCLUSION: The only beneficial impact of PAT was on the prevalence of gonococcal infections among FSWs 9 months after the beginning of the intervention. Although PAT could be more effective in other circumstances, for instance, in the early stages of a program for FSWs, it can not be recommended at present as a routine strategy to control cervical infections among FSWs.

Influence of the physical state of phospholipid monolayers on protein binding.

Langmuir monolayers were used to characterize the influence of the physical state of phospholipid monolayers on the binding of protein Retinis Pigmentosa 2 (RP2). The binding parameters of RP2 (maximum insertion pressure (MIP), synergy and ΔΠ(0)) in monolayers were thus analyzed in the presence of phospholipids bearing increasing fatty acyl chain lengths at temperatures where their liquid-expanded (LE), liquid-condensed (LC), or solid-condensed (SC) states can be individually observed. The data show that a larger value of synergy is observed in the LC/SC states than in the LE state, independent of the fatty acyl chain length of phospholipids. Moreover, both the MIP and the ΔΠ(0) increase with the fatty acyl chain length when phospholipids are in the LC/SC state, whereas those binding parameters remain almost unchanged when phospholipids are in the LE state. This effect of the phospholipid physical state on the binding of RP2 was further demonstrated by measurements performed in the presence of a phospholipid monolayer showing a phase transition from the LE to the LC state at room temperature. The data collected are showing that very similar values of MIP but very different values of synergy and ΔΠ(0) are obtained in the LE (below the phase transition) and LC (above the phase transition) states. In addition, the binding parameters of RP2 in the LE (below the phase transition) as well as in the LC (above the phase transition) states were found to be indistinguishable from those where single LC and LE states are respectively observed. The preference of RP2 for binding phospholipids in the LC state was then confirmed by the observation of a large modification of the shape of the LC domains in the phase transition. Therefore, protein binding parameters can be strongly influenced by the physical state of phospholipid monolayers. Moreover, measurements performed with the α/ß domain of RP2 strongly suggest that the ß helix of RP2 plays a major role in the preferential binding of this protein to phospholipids in the LC state.

Depression and the risk of hospitalization in type 2 diabetes patients: A nested case-control study accounting for non-persistence to antidiabetic treatment.

INTRODUCTION: Depression is one of the most common comorbidities of type 2 diabetes. The relationship between these two diseases seems to be bidirectional. Both conditions separately lead to significant morbidity and mortality, including hospitalization. Moreover, depression is associated with non-persistence with antidiabetic drugs. OBJECTIVES: To measure the effect of depression on morbidity and particularly on all-cause, diabetes-related, cardiovascular-related and major cardiovascular events-related hospitalization, adjusting for non-persistence to antidiabetic drugs and other confounders. METHODS: We performed a nested case-control study within a cohort of type 2 diabetic individuals initiating antidiabetic drugs. Using the health administrative data of the province of Quebec, Canada, we identified all-cause, diabetes-related, cardiovascular-related and major cardiovascular hospitalizations during a maximum follow-up of eight years after the initiation of antidiabetic drug treatment. A density sampling method matched all cases with up to 10 controls by age, sex, and the Elixhauser comorbidity index. The effect of depression on hospitalization was estimated using conditional logistic regressions adjusting for non-persistence to antidiabetic drug treatment and other variables. RESULTS: We identified 41,550 all-cause hospitalized cases, of which 34,437 were related to cardiovascular (CV) diseases, 29,584 to diabetes, and 13,867 to major CV events. Depression was diagnosed in 2.51% of all-cause hospitalizations and 1.16% of matched controls. 69.11% of cases and 72.59% of controls were on metformin monotherapy. The majority (71.62% vs 75.02%, respectively) stayed on metformin monotherapy without adding or switching drugs during follow-up. Non-persistence was at similar rates (about 30%) in both groups. In the multivariable analyses, depression was associated with an increased risk for all-cause hospitalizations, with odds ratios (ORs) ranging from 2.21 (95% CI: 2.07-2.37) to 1.32 (95% CI: 1.22-1.44) according to the model adjustment (from the univariate to the fully adhjusted). CONCLUSION: Depression increased the risk of all-cause hospitalizations among patients treated for diabetes, even after accounting for non-persistence and other potentially confounding factors. These results stress the impact of depression on diabetic patients' use of health care resources.

A description of self-medication with cannabis among adults with legal access to cannabis in Quebec, Canada.

OBJECTIVE: Cannabis is increasingly used for medical purposes, particularly in countries like Canada where cannabis was recently legalized for recreational use. We aimed to assess self-medication with cannabis post-cannabis legalization among adults in the Canadian province of Quebec. METHODS: This is a cross-sectional online survey of a self-selected convenience sample conducted in Quebec, Canada, from November 2020 to January 2021. Individuals aged ≥ 21 years who endorsed using cannabis bought in legal recreational cannabis stores to self-medicate a health condition were included. Data were analyzed using descriptive statistics and stratified according to sex, age, and the type of cannabis use (exclusively medical versus medical and recreational use). RESULTS: Four hundred eighty-nine participants were included. The median age was 34 years, and 48% were women. About 25% reported exclusive medical use of cannabis. Treated conditions included anxiety (70%), insomnia (56%), pain (53%), depression (37%), and many others. Reasons for not consulting in cannabis clinics included lack of information (52%), the complexity of the process (39%), accessibility of cannabis clinics (23%), and others. Tetrahydrocannabinol (THC) dosage > 20% was reported by 32%. Smoking was the main route of use (81%). Possession of prescribed drugs was reported by 56%. Professionals consulted for information on cannabis included recreational cannabis store agents (36%), physicians (29%), and others. Overall, significant differences were observed for many of the comparisons according to sex, age, and the type of cannabis use. CONCLUSIONS: Many conditions are self-medicated with cannabis. The use of high doses of cannabis, smoking as a preferred method of use, and concurrent use of other medications may pose some risks to individuals. Addressing the reported barriers to medical access to cannabis is urgently needed.

Analysis of the contribution of saturated and polyunsaturated phospholipid monolayers to the binding of proteins.

The binding of peripheral proteins to membranes results in different biological effects. The large diversity of membrane lipids is thought to modulate the activity of these proteins. However, information on the selective binding of peripheral proteins to membrane lipids is still largely lacking. Lipid monolayers at the air/water interface are useful model membrane systems for studying the parameters responsible for peripheral protein membrane binding. We have thus measured the maximum insertion pressure (MIP) of two proteins from the photoreceptors, Retinitis pigmentosa 2 (RP2) and recoverin, to estimate their binding to lipid monolayers. Photoreceptor membranes have the unique characteristic that more than 60% of their fatty acids are polyunsaturated, making them the most unsaturated natural membranes known to date. These membranes are also thought to contain significant amounts of saturated phospholipids. MIPs of RP2 and recoverin have thus been measured in the presence of saturated and polyunsaturated phospholipids. MIPs higher than the estimated lateral pressure of biomembranes have been obtained only with a saturated phospholipid for RP2 and with a polyunsaturated phospholipid for recoverin. A new approach was then devised to analyze these data properly. In particular, a parameter called the synergy factor allowed us to highlight the specificity of RP2 for saturated phospholipids and recoverin for polyunsaturated phospholipids as well as to demonstrate clearly the preference of RP2 for saturated phospholipids that are known to be located in microdomains.

Depression but not non-persistence to antidiabetic drugs is associated with mortality in type 2 diabetes: A nested case-control study.

AIMS: To measure the effect of depression on mortality of individuals newly treated with antidiabetic drugs, accounting for non-persistence to treatment. METHODS: We conducted a nested case-control study within a cohort of newly treated individuals with diabetes. Using Quebec administrative data, we identified all-cause, diabetes-related, cardiovascular-related and major cardiovascular event deaths during a maximum follow-up of eight years. Each case was matched with up to 10 controls by age, sex, follow-up, and comorbidity index. We used conditional logistic regressions to estimate the effect of depression on mortality, adjusting for non-persistence to antidiabetic drug treatment, and other variables. RESULTS: We retrieved 13,558 deaths, of which 3,652 were related to cardiovascular diseases, 2,112 to major cardiovascular events, and 311 to diabetes. Depression was associated with an increased risk of all-cause and cardiovascular-related deaths, with adjusted odds ratios (ORs) ranging from 1.32 (95% CI: 1.21-1.45) to 1.72 (95% CI: 1.57-1.88) depending on the model, but not with diabetes-related mortality. CONCLUSION: Depression is independently associated with all-cause and cardiovascular-related mortality in individuals with type 2 diabetes, even when adjusting for non-persistence to antidiabetic drug treatment. Identifying risk factors for depression and implementing a screening and proper treatment for depression may help reducing mortality.

Ecological analysis of the association between high-risk population parameters and HIV prevalence among pregnant women enrolled in sentinel surveillance in four Southern India states.

BACKGROUND: The HIV epidemic is very heterogeneous at the district level in the four Southern states of India most affected by the epidemic and where transmission is mainly heterosexual. The authors carried out an ecological study of the relationship between high-risk population parameters and HIV prevalence among pregnant women (ANC HIV prevalence). METHODS: The data used in this study included: ANC HIV prevalence available from the National AIDS Control Organization (dependent variable); data on prevalence of HIV and other sexually transmitted infections among female sex workers (FSWs), their clients and high-risk men who have sex with men (HR-MSM) from studies carried out in 24 districts under Avahan; data on clients' volume reported by FSWs and on the size estimates of FSWs and HR-MSM in each district; and census data. The latter two sets of data were used to estimate the percentage of female (male) adults who are FSWs (HR-MSM). The latter was also multiplied by HIV prevalence in FSWs (HR-MSM) to obtain the percentage of HIV-positive FSWs (HR-MSM) in the adult female (male) population. Linear regression was used for statistical analyses. RESULTS: In univariate analyses, HIV (r=0.59, p=0.002) and HSV-2 (r=0.49, p=0.014) prevalence among FSWs and mean number of clients in the last week reported by FSWs (r=0.43, p=0.036) were significant predictors of ANC HIV prevalence. In multivariate analysis, only FSW HIV prevalence remained significant. CONCLUSIONS: This ecological study suggests that there is a link between HIV prevalence among FSWs and the spread of HIV to the general population in Southern India. Such an observation supports the rationale of interventions targeted at the sex industry.

Interim modelling analysis to validate reported increases in condom use and assess HIV infections averted among female sex workers and clients in southern India following a targeted HIV prevention programme.

OBJECTIVES: This study assesses whether the observed declines in HIV prevalence since the beginning of the 'Avahan' India HIV/AIDS prevention initiative are consistent with self-reported increases in condom use by female sex workers (FSWs) in two districts of southern India, and provides estimates of the fraction of new infections averted among FSWs and clients due to increases in condom use in commercial sex after 2004. METHODS: A deterministic compartmental model of HIV/sexually transmitted infection (STI) transmission incorporating heterogeneous sexual behaviour was developed, parameterised and fitted using data from two districts in Karnataka, India. Three hypotheses of condom use among FSWs were tested: (H(0)), that condom use increased in line with reported FSW survey data prior to the Avahan initiative but remained constant afterwards; (H(1)) that condom use increased following the Avahan initiative, in accordance with survey data; (H(2)) that condom use increased according to estimates derived from condom distribution data. The proportion of fits to HIV/STI prevalence data was examined to determine which hypothesis was most consistent. RESULTS: For Mysore 0/36/82.7 fits were identified per million parameter sets explored under hypothesis H(0)/H(1)/H(2), respectively, while for Belgaum 9.7/8.3/0 fits were identified. The HIV epidemics in Belgaum and Mysore are both declining. In Mysore, increases in condom use during commercial sex between 2004 and 2009 may have averted 31.2% to 47.4% of new HIV infections in FSWs, while in Belgaum it may have averted 24.8% to 43.2%, if there was an increase in condom use. DISCUSSION: Increased condom use following the Avahan intervention is likely to have played a role in curbing the HIV epidemic in Mysore. In Belgaum, given the limitations in available data, this method cannot be used alone to decide if there has been an increase in condom use.

TREATMENT COMPLETION AND IMPLEMENTATION BY PATIENTS INITIATING TICAGRELOR.

BACKGROUND: In secondary prevention of adverse events and death following acute coronary syndrome, patients may benefit from adhering to a ticagrelor treatment. OBJECTIVES: The authors assessed the proportion of new ticagrelor users who completed 12 months of treatment, explored the factors associated with treatment completion and, among the completers, evaluated the 12-month treatment implementation. METHODS: A retrospective administrative health database inception cohort study was conducted in a population that included Quebec residents ≥18 years of age who initiated ticagrelor between January 1, 2012 and March 31, 2014. A patient still on ticagrelor at the end of the 12-month period after treatment initiation was considered to have completed the treatment. Factors associated with treatment completion were identified using log-binomial regression. Implementation was assessed using the proportion of days covered (PDC). RESULTS: Of the 3,600 patients, 2,235 (62.1%) completed 12 months of treatment. The patients who were more likely to complete their treatment included those who had visited a general practitioner, had a percutaneous coronary intervention, used a statin or fibrate, and those who used an antihypertensive drug during the year preceding the ticagrelor treatment initiation. Older patients, those with atrial fibrillation, those who had ≥ 6 physician visits and those who used an anticoagulant were less likely to complete the 12-month treatment. The median PDC was 96.2%. CONCLUSION: Treatment completion might be improved. Among patients who completed the treatment, implementation was high. The factors associated with completion could help to identify patients who might benefit from interventions that aim to optimize treatment completion.

The Effect of Stance Width and Anthropometrics on Joint Range of Motion in the Lower Extremities during a Back Squat.

The purpose of this study was to assess whether changing the stance width has an effect on the range of motion of hip flexion, knee flexion, and ankle dorsiflexion during an unloaded back squat, and whether these joint movements are affected by anthropometric differences. Thirty-two healthy, young adults performed unloaded back squats at three different stance widths, normalized to pelvic width. Joint angles were assessed using electromagnetic motion capture sensors on the sacrum, and thigh, shank and foot of the dominant leg. ANOVA comparison of joint angles for the three stance widths, at 10° intervals of thigh orientation during the squat, indicated that joint angles tended to be larger when stance width was narrower, with the most significant effects on ankle dorsiflexion. A greater trunk/thigh length ratio (relatively long trunk) also tended to be associated with lower ankle and knee angles, while a greater thigh/shank length ratio (relatively long thigh) tended to be associated with higher ankle and knee angles, for the two narrower stance widths. The most practical implication of our findings is that individuals with limited ankle dorsiflexion, or with particularly long legs / thighs, may benefit from a wider stance width when squatting.

Prevalence of HIV and hepatitis C virus infections among inmates of Quebec provincial prisons.

BACKGROUND: To determine the prevalence of HIV and hepatitis C virus (HCV) infections and examine risk factors for these infections among inmates in Quebec provincial prisons. METHODS: Anonymous cross-sectional data were collected from January to June 2003 for men (n = 1357) and women (n = 250) who agreed to participate in the study and who completed a self-administrated questionnaire and provided saliva samples. RESULTS: The prevalence of HIV infection was 2.3% among the male participants and 8.8% among the female participants. The corresponding prevalence of HCV infection was 16.6% and 29.2%, respectively. The most important risk factor was injection drug use. The prevalence of HIV infection was 7.2% among the male injection drug users and 0.5% among the male non-users. Among the women, the rate was 20.6% among the injection drug users, whereas none of the non-users was HIV positive. The prevalence of HCV infection was 53.3% among the male injection drug users and 2.6% among the male non-users; the corresponding values among the women were 63.6% and 3.5%. INTERPRETATION: HIV and HCV infections constitute an important public health problem in prison, where the prevalence is affected mainly by a high percentage of injection drug use among inmates.

How to gather useful and valuable information from protein binding measurements using Langmuir lipid monolayers.

This review presents data on the influence of various experimental parameters on the binding of proteins onto Langmuir lipid monolayers. The users of the Langmuir methodology are often unaware of the importance of choosing appropriate experimental conditions to validate the data acquired with this method. The protein Retinitis pigmentosa 2 (RP2) has been used throughout this review to illustrate the influence of these experimental parameters on the data gathered with Langmuir monolayers. The methods detailed in this review include the determination of protein binding parameters from the measurement of adsorption isotherms, infrared spectra of the protein in solution and in monolayers, ellipsometric isotherms and fluorescence micrographs.

No increase in HIV incidence observed in a cohort of men who have sex with other men in Montreal.

To monitor HIV incidence we tested a cohort of men who have sex with men in Montreal for HIV every 6 months. Between 1996 and 2001, 17 out of 1244 participants seroconverted, for an HIV incidence of 0.56 per 100 person-years (py) (95% CL 0.29, 0.83). The incidence decreased over the study period, from 0.75 to 0.34 per 100 py; which was not statistically significant. An in-depth evaluation of the situation in Montreal could identify useful lessons for prevention efforts elsewhere.