Implementation of an integrated primary care prevention and management program for chronic low back pain (LBP): patient-reported outcomes and predictors of pain interference after six months.

BACKGROUND: Integrated primary care programs for patients living with chronic pain which are accessible, interdisciplinary, and patient-centered are needed for preventing chronicity and improving outcomes. Evaluation of the implementation and impact of such programs supports further development of primary care chronic pain management. This study examined patient-reported outcomes among individuals with low back pain (LBP) receiving care in a novel interdisciplinary primary care program. METHODS: Patients were referred by primary care physicians in four regions of Quebec, Canada, and eligible patients received an evidence-based interdisciplinary pain management program over a six-month period. Patients were screened for risk of chronicity. Patient-reported outcome measures of pain interference and intensity, physical function, depression, and anxiety were evaluated at regular intervals over the six-month follow-up. A multilevel regression analysis was performed to evaluate the association between patient characteristics at baseline, including risk of chronicity, and change in pain outcomes. RESULTS: Four hundred and sixty-four individuals (mean age 55.4y, 63% female) completed the program. The majority (≥ 60%) experienced a clinically meaningful improvement in pain intensity and interference at six months. Patients with moderate (71%) or high risk (81%) of chronicity showed greater improvement in pain interference than those with low risk (51%). Significant predictors of improvement in pain interference included a higher risk of chronicity, younger age, female sex, and lower baseline disability. CONCLUSION: The outcomes of this novel LBP program will inform wider implementation considerations by identifying key components for further effectiveness, sustainability, and scale-up of the program.

Having More Tender Than Swollen Joints Is Associated With Worse Patient-Reported Outcomes in Patients With Early RA.

BACKGROUND/OBJECTIVE: In patients with rheumatoid arthritis (RA), high tender-swollen joint differences (TSJDs) have been associated with worse outcomes. A better understanding of the phenotype and impact of high TSJD on patient-reported outcomes (PROs) in early RA may lead to earlier personalized treatment targeting domains that are important to patients today. Our objectives were to evaluate the impact of TSJD on updated PROs in patients with early RA over 1 year and to determine differences in associations by joint size. METHODS: This longitudinal cohort study followed patients with active, early RA enrolled in the Canadian Early Arthritis Cohort between 2016 and 2022, who completed clinical assessments and PROMIS-29 measures over 1 year. Twenty-eight joint counts were performed and TSJDs calculated. Adjusted associations between TSJD and PROMIS-29 scores were estimated using separate linear-mixed models. Separate analyses of large versus small-joint TJSDs were performed. RESULTS: Patients with early RA (n = 547; 70% female; mean [SD] age, 56 [15] years; mean [SD] symptom duration, 5.3 [2.9] months) were evaluated. A 1-point increase in TSJD was significantly associated with worse PROMIS T-scores in all domains: physical function (adjusted regression coefficient, -0.27; 95% confidence interval [CI], -0.39, -0.15), social participation (adjusted regression coefficient, -0.34; 95% CI, -0.50, -0.19), pain interference (adjusted regression coefficient, 0.49; 95% CI, 0.35, 0.64), sleep problems (adjusted regression coefficient, 0.29; 95% CI, 0.16, 0.43), fatigue (adjusted regression coefficient, 0.34; 95% CI, 0.18, 0.50), anxiety (adjusted regression coefficient, 0.23; 95% CI, 0.08, 0.38), and depression (adjusted regression coefficient, 0.20; 95% CI, 0.06, 0.35). Large-joint TSJD was associated with markedly worse PROs compared with small-joint TSJD. CONCLUSIONS: Elevated TSJD is associated with worse PROs particularly pain interference, social participation, and fatigue. Patients with more tender than swollen joints, especially large joints, may benefit from earlier, targeted therapeutic interventions.

Having More Tender Than Swollen Joints is Associated With Worse Function and Work Impairment in Patients With Early Rheumatoid Arthritis.

OBJECTIVE: Patients with early rheumatoid arthritis (RA) may present with more tender than swollen joints, which can persist. Elevated tender-swollen joint difference (TSJD) is often challenging, because there may be multiple causes and it may contribute to overestimating disease activity. Little is known about the phenotype and impact of TSJDs on patient function. Our objective was to evaluate the impact of TSJD on functional outcomes in early RA and to see whether associations vary by joint size. METHODS: Data were from patients with active, early RA (≤12 months) enrolled in the Canadian Early Arthritis Cohort, who completed assessments of general function (Multidimensional Health Assessment Questionnaire [MDHAQ]), upper extremity (UE) function (Quality of Life in Neurological Disorders [Neuro-QoL] UE scale), and work/activity impairment (Work Productivity and Activity Impairment RA) over their first year of follow-up. A total of 28 joint counts were performed. TSJDs were calculated. Adjusted associations between TSJDs and functional outcomes were estimated in separate multivariable linear mixed effects models. Separate analyses were performed for large- versus small-joint TSJD. RESULTS: Patients (N = 547) were 70% female, mean age 56 (SD 15) years, mean disease duration 5.3 (SD 2.9) months. At baseline, 287 (52%) had TSJD >0 (43% involved large joints and 34% small joints), decreasing to 32% at 12 months. A one-point increase in TSJD was significantly associated with worse function (MDHAQ: adjusted mean change 0.10, 95% confidence interval [CI] 0.08-0.13; Neuro-QoL UE function T score: adjusted mean change -0.59, 95% CI -0.76 to -0.43; and greater work impairment: adjusted mean change 1.95%, 95% CI 0.85%-3.05%). Higher large-joint TSJDs were associated with the worst functional outcomes. CONCLUSION: Having more tender than swollen joints is common in early RA and is associated with worse function, most notably when involving large joints. Early identification and targeted intervention strategies may be needed.

Exploring if and how evidence-based practice of occupational and physical therapists evolves over time: A longitudinal mixed methods national study.

BACKGROUND: Occupational therapists (OTs) and physiotherapists (PTs) are expected to provide evidence-based services to individuals living with disabilities. Despite the emphasis on evidence-based practice (EBP) by professional entry-level programs and professional bodies, little is known about their EBP competencies upon entry to practice and over time or what factors impact EBP use. The aim of the study was to measure and understand how EBP evolves over the first three years after graduation among Canadian OTs and PTs, and how individual and organizational factors impact the continuous use of EBP. METHODS: A longitudinal, mixed methods sequential explanatory study. We administered a survey questionnaire measuring six EBP constructs (knowledge, attitudes, confidence, resources, use of EBP and evidence-based activities) annually, followed by focus group discussions with a subset of survey participants. We performed group-based trajectory modeling to identify trajectories of EBP over time, and a content analysis of qualitative data guided by the Theoretical Domains Framework. RESULTS: Of 1700 graduates in 2016-2017, 257 (response rate = 15%) responded at baseline (T0) (i.e., at graduation), and 83 (retention rate = 32%), 75 (retention rate = 29%), and 74 (retention rate = 29%) participated at time point 1 (T1: one year into practice), time point 2 (T2: two years into practice, and time point 3 (T3: three years into practice) respectively. Group-based trajectory modeling showed four unique group trajectories for the use of EBP. Over 64% of participants (two trajectories) showed a decline in the use of EBP over time. Fifteen practitioners (7 OTs and 8 PTs) participated in the focus group discussions. Personal and peer experiences, client needs and expectations, and availability of resources were perceived to influence EBP the most. CONCLUSIONS: Though a decline in EBP may be concerning, it is unclear if this decline is clinically meaningful and whether professional expertise can offset such declines. Stakeholder-concerted efforts towards the common goal of promoting EBP in education, practice and policy are needed.

"From Where I Stand": using multiple anchors yields different benchmarks for meaningful improvement and worsening in the rheumatoid arthritis flare questionnaire (RA-FQ).

PURPOSE: The Rheumatoid Arthritis Flare Questionnaire (RA-FQ) is a patient-reported measure of disease activity in RA. We estimated minimal and meaningful change from the perspective of RA patients, physicians, and using a disease activity index. METHODS: Data were from 3- to 6-month visits of adults with early RA enrolled in the Canadian Early Arthritis Cohort. Participants completed the RA-FQ, the Patient Global Assessment of RA, and the Patient Global Change Impression at consecutive visits. Rheumatologists recorded joint counts and MD Global. Clinical Disease Activity Index (CDAI) scores were computed. We compared mean RA-FQ change across categories using patients, physicians, and CDAI anchors. RESULTS: The 808 adults were mostly white (84%) women (71%) with a mean age of 55 and moderate-high disease activity (85%) at enrollment. At V2, 79% of patients classified their RA as changed; 59% were better and 20% were worse. Patients reporting they were a lot worse had a mean RA-FQ increase of 8.9 points, whereas those who were a lot better had a -6.0 decrease. Minimal worsening and improvement were associated with a mean 4.7 and - 1.8 change in RA-FQ, respectively, while patients rating their RA unchanged had stable scores. Physician and CDAI classified more patients as worse than patients, and minimal and meaningful RA-FQ thresholds differed by group. CONCLUSION: Thresholds to identify meaningful change vary by anchor used. These data offer new evidence demonstrating robust psychometric properties of the RA-FQ and offer guidance about improvement or worsening, supporting its use in RA care, research, and decision-making.

Ambient exposures to selected volatile organic compounds and the risk of prostate cancer in Montreal.

Little is known about environmental factors that may increase the risk of prostate cancer. We estimated associations between incident prostate cancer and environmental concentrations of five ambient volatile organic compounds (VOCs): benzene; n-decane; ethylbenzene; hexane; and 1,2,4-trimethylbenzene. Methods: This study is based on a population-based case-control study of incident prostate cancer (PROtEuS) in men ≤ 75 years of age living in Montreal, Canada, in 2005 to 2012. We included 1172 cases and 1177 population controls. We had personal information, lifetime residential addresses, occupational exposures, and a variety of area-wide covariables. We inferred concentrations of the five VOCs using Bayesian geostatistical models using data from a dense environmental survey conducted in Montreal in 2005 to 2006. We used different sets of adjustments to estimate odds ratios (OR) and confidence intervals. Results: We found nonlinear associations such that the ORs increased monotonically and then either flattened or fell off with increased exposures. The model that contained other environmental variables and contextual variables led to lower ORs and results were similar when we restricted analyses to controls recently screened or tested for prostate cancer or cases with low- or high-grade tumors. A change from the 5th to 25th percentile in mean environmental benzene levels led to an adjusted OR of 2.00 (95% confidence interval = 1.47, 2.71). Conclusion: We found positive associations between prostate cancer and concentrations of benzene and ethylbenzene, independently of previous testing for prostate cancer or tumor grade, suggesting that exposure to certain ambient VOCs may increase incidence.

Predictors of Influenza Vaccination in Early Rheumatoid Arthritis 2017-2021: Results From the Canadian Early Arthritis Cohort.

OBJECTIVE: Adults with rheumatoid arthritis (RA) are at a higher risk for infections, including influenza and related complications. We identified influenza vaccination coverage in adults newly diagnosed with RA and examined sociodemographic RA characteristics and attitudes associated with vaccination. METHODS: We used data from patients enrolled in the Canadian Early Arthritis Cohort between September 2017 and February 2021. At enrollment, participants reported their vaccination status in the previous year and completed the Beliefs About Medicines Questionnaire (BMQ). Clinical data were obtained from medical records. Logistic regression was used to identify predictors of vaccination in the year after RA diagnosis. RESULTS: The baseline analytic sample of 431 patients were mostly White (80%) women (67%) with a mean age of 56 (SD 14) years. Prediagnosis, influenza vaccine coverage was 38%, increasing to 46% post diagnosis in the longitudinal sample (n = 229). Participants with previous influenza vaccination (odds ratio [OR] 15.33; 95% confidence interval [CI] 6.37-36.90), on biologics or JAKs (OR 5.42; 95% CI 1.72-17.03), and with a higher change in BMQ Necessity-Concerns Differential scores (OR 1.08; 95% CI 1.02-1.15) had greater odds, whereas women (OR 0.32; 95% CI 0.14-0.71), participants with a non-White racial background (OR 0.13; 95% CI 0.04-0.51), and participants currently smoking (OR 0.09; 95% CI 0.02-0.37) had lower odds of influenza vaccine coverage. CONCLUSION: Influenza vaccination coverage in patients with early RA remains below national targets in adults living with a chronic condition. Discussing vaccine history and medication attitudes at initial clinic visits with new patients with RA may enhance vaccine acceptance and uptake.

A Bridge Too Far? Real-World Practice Patterns of Early Glucocorticoid Use in the Canadian Early Arthritis Cohort.

OBJECTIVE: To describe patterns of glucocorticoid use in a large real-world cohort with early rheumatoid arthritis (RA) and assess the impact on disease activity and treatment. METHODS: Data are from adults with new RA (≤1 year) recruited to the Canadian Early Arthritis Cohort (CATCH) and are stratified on the basis of whether a person was prescribed oral glucocorticoids within 3 months of study entry. Disease activity was compared over 24 months. Mixed-effects logistic regression was used for adjusted odds ratios (aORs) of escalation to biologics separately for 12 and 24 months, with random effects terms to account for prescribing patterns clustering by study site. RESULTS: Among 1891 persons, 30% received oral steroids. Users were older, were less often employed, and had shorter disease duration and higher disease activity. Disease activity improved over time, with early glucocorticoid users starting at higher levels of disease activity. Participants with early oral glucocorticoids were more likely to be on a biologic at 12 months (aOR = 2.4; 95% confidence interval [CI], 1.5-3.7) and 24 months (aOR = 1.9; 95% CI, 1.3-3.0). Despite Canadian clinical practice guidelines to limit corticosteroid use to short-term or 'bridge' therapy, 30% of patients who used oral glucocorticoids still used them 2 years later. CONCLUSION: Early steroids were prescribed sparingly in CATCH and were often indicative of more active baseline disease as well as the need for progression to biologics.

Individual and organizational factors associated with evidence-based practice among physical and occupational therapy recent graduates: A cross-sectional national study.

BACKGROUND: Occupational therapy (OT) and physical therapy (PT) programs in Canada have moved to graduate-level entry education to address graduates' readiness for evidence-based practice (EBP). Whether rehabilitation professionals with advanced training in EBP are meeting their responsibilities as evidence-based professionals upon entry into practice and the factors that influence the use of evidence is unclear. The aim of this study was to examine the individual and organizational factors associated with the use of EBP and supporting evidence-based activities among graduates of professional OT and PT master's programs. METHODS: A cross-sectional design using a survey of recent graduates of the 29 OT and PT programs in Canada. The survey measured six constructs supportive of EBP (ie, knowledge, attitudes, confidence, organizational resources, actual use of EBP, and evidence-based activities). Analyses consisted of descriptive statistics to characterize the sample and the different variables and ordinal multivariate regression analysis. RESULTS: 257 graduates (15%) completed the survey. Attitudes towards EBP was positively associated both with evidence-based activities (odds ratio = 1.36 with a 95% CI: 1.22 to 1.52) and use of EBP (odds ratio = 1.23 with a 95% CI: 1.12 to 1.36); greater confidence was related to greater use of EBP (OR = 1.12, 95% CI: 1.01 to 1.24); and working in a private practice setting was found to be related to performing more evidence-based activities (odds ratio = 3.15, 95% CI: 1.40 to 7.12). CONCLUSIONS: Despite a greater focus on EBP knowledge in these curricula across Canada, knowledge was not related to EBP use nor evidence-based activities upon entry into practice. On the other hand, attitudes, confidence and working in private practice were. University programs should consider curricular strategies that increase the use of EBP, provide opportunities to engage in evidence-based activities with an emphasis on promoting the development of positive attitudes towards EBP and increasing learners' confidence in their ability to be evidence-based professionals.

Treatment Strategies in Early Rheumatoid Arthritis Methotrexate Management: Results From a Prospective Cohort.

OBJECTIVE: To assess real-world practice patterns surrounding treatment initiation and adjustments over time for methotrexate (MTX) and non-MTX-based treatment strategies in early rheumatoid arthritis (RA). METHODS: We studied a multicenter, incident early RA cohort (enrolled 2007-2017 within 1 year of symptoms) who fulfilled American College of Rheumatology/European League Against Rheumatism criteria. Adult patients with RA were eligible if treatment with MTX (± other disease-modifying antirheumatic drugs [DMARDs]) was initiated within 90 days of cohort entry. We compared time until treatment change for 4 initial MTX-based therapies and time to second treatment change after the first change. The definition of treatment change included changing of route for MTX monotherapy, adding or stopping a DMARD or biologic, and changing dose/frequency of a DMARD or biologic. RESULTS: There was great variability of treatment at initiation and during therapy adjustment. In 1,484 patients with early RA, the majority initiated MTX monotherapy (oral or subcutaneous [SC]). Patients receiving SC MTX monotherapy changed treatment less (45% versus 79%) and remained on treatment longer (hazard ratio [HR] 0.52 [95% confidence interval (95% CI) 0.4-0.67]) than those receiving oral MTX monotherapy. Most therapy adjustments involved adding a DMARD or changing to a non-MTX DMARD. Those adults taking biologics and who were receiving triple therapy had a longer time without treatment change (HR 0.26 [95% CI 0.16-0.42] and HR 0.57 [95% CI 0.38-0.85], respectively). CONCLUSION: We found large variability in the way MTX-based therapies are prescribed in clinical practice. Our findings support the use of SC MTX monotherapy or MTX combination as initial therapy. For subsequent treatment after initial MTX-based therapy, those patients initiating either biologics or triple therapy had a longer time to treatment change than oral MTX monotherapy.

Determinants Of Patient Experience With Low Back Pain Interdisciplinary Care: A Pre-Post Interventional Study.

BACKGROUND AND PURPOSE: Measuring patients' experiences of health services has become an essential part of quality of care reporting and a means for identifying opportunities for improvement. This study aimed to evaluate change in patient experience in an interdisciplinary primary care program and to estimate the impact on patient experience of sociodemographic, function, pain and general health status, resource utilization, and process variables. PATIENTS AND METHODS: A 6-month interdisciplinary care program for individuals with low back pain (LBP) was implemented at four primary care settings and evaluated using an observational pre/post study design. The change in patient experience was evaluated using the Patient Assessment of Chronic Illness Care questionnaire (PACIC) completed at baseline and 6 months post-intervention (n=132). Descriptive and multivariable analyses were performed using SAS version 9.3. RESULTS: The average patient age was 57 (SD: 14) years of age and the majority were female (53%). The mean overall PACIC score was 2.6 (SD: 1.1) at baseline and 3.6 (SD: 0.9) at 6 months. The experience of care improved for 62% of the participants based on the minimal clinically important difference (MCID). No significant determinants of overall PACIC change score were identified in the multivariable regression models. CONCLUSION: The lack of association of hypothesized determinants requires further examination of the properties of the PACIC and with a larger sample. Future investigation is needed on the relationship between improved patient experience and outcomes.

Support for teams, technology and patient involvement in decision-making associated with support for patient-centred care.

OBJECTIVE: Patient-centred care is recommended to transform healthcare delivery to improve the quality and safety of healthcare. This study aimed to assess the determinants of support for attributes of patient-centred care (PCC) from Canadian public and professionals' perspectives. DESIGN: A national population-based survey, the Health Care in Canada Survey. SETTING: Canada. PARTICIPANTS: One-thousand Canadian adults, 101 doctors, 100 nurses, 100 pharmacists and 104 administrators, randomly selected from online panels based on multiple source recruitment. INTERVENTION: None. MAIN OUTCOME MEASURE: Support for PCC, assessed using a summary score across seven items. RESULTS: Of 1000 Canadian public adults surveyed, 51% were female, 74% were living with another person, and 62% had at least one chronic condition. Only 18% of health professionals were working in teams. Multivariable regression models showed that work in teams (0.24, 95%CI: 0.20, 0.28), use of e-technology (0.29, 95%CI: 0.17, 0.42), and patient older age (0.59, 95%CI: 0.32, 0.86) and involvement in decision-making (0.42, 95%CI: 0.30, 0.55) were significantly associated with higher support for PCC while lower adherence to medications (-0.81, 95%CI: -1.16, -0.47) was associated with a decreased support for attributes of PCC. CONCLUSIONS: The findings confirmed that perceptions of requiring health professionals to work in teams and the use of technology in healthcare are associated with support for PCC from both the public and health professionals. Programs to accelerate the implementation of healthcare teams supported by information and communication technologies are needed to deliver PCC, particularly for individuals living with chronic conditions.

Age, gender, and current living status were associated with perceived access to treatment among Canadians using a cross sectional survey.

BACKGROUND: Access, particularly timely access, to care is the Canadian public's most important healthcare concern. The drivers of perceived appropriateness of access to care among patients with at least one chronic health condition (CHC) are not, however, well defined. This study evaluated whether personal characteristics, self-reported health status and care received were associated with patients' perception of effective access in managing a chronic illness. METHODS: The study population (n = 619) was drawn from a representative sample of the adult Canadian population who reported having ≥1 CHC in the 2013-2014 Health Care in Canada survey. Ordinal regression, with the continuation ratio model, was used to evaluate association of perceived level of access to treatment with socio-demographic factors, perceived health status and care utilization experience. RESULTS: Factors most closely associated with patients' satisfaction with care access were: age, sex, current cohabitation, care affordability, and availability of support and information to help manage their CHCs. Individuals, particularly females, < 35 years, currently living alone, with poor access to professional support or information and who feel affordability of care has worsened over the past five years were more likely to report a poorer level of treatment access. CONCLUSIONS: Individuals living alone, who are younger, and women may be especially susceptible to lower perceived access to care of CHCs and a sense of pessimism about things not getting better. Further evaluation of the reasons behind these findings may help develop effective strategies to assist these populations to access the care they need.

Household air pollution and measures of blood pressure, arterial stiffness and central haemodynamics.

OBJECTIVE: We evaluated the exposure-response associations between personal exposure to air pollution from biomass stoves and multiple vascular and haemodynamic parameters in rural Chinese women. METHODS: We analysed the baseline information from a longitudinal study in southwestern China. Women's brachial and central blood pressure and pulse pressure, carotid-femoral pulse wave velocity and augmentation index, and their 48-hour personal exposures to fine particulate matter (PM2.5) and black carbon were measured in summer and winter. We evaluated the associations between exposure to air pollution and haemodynamic parameters using mixed-effects regression models adjusted for known cardiovascular risk factors. RESULTS: Women's (n=205, ages 27-86 years) exposures to PM2.5 and black carbon ranged from 14 µg/m3 to 1405 µg/m3 and 0.1-121.8 µg/m3, respectively. Among women aged ≥50 years, increased PM2.5 exposure was associated with higher systolic (brachial: 3.5 mm Hg (P=0.05); central: 4.4 mm Hg (P=0.005)) and diastolic blood pressure (central: 1.3 mm Hg (P=0.10)), higher pulse pressure (peripheral: 2.5 mm Hg (P=0.05); central: 2.9 mm Hg (P=0.008)) and lower peripheral-central pulse pressure amplification (-0.007 (P=0.04)). Among younger women, the associations were inconsistent in the direction of effect and not statistically significant. Increased PM2.5 exposure was associated with no difference in pulse wave velocity and modestly higher augmentation index though the CI included zero (1.1%; 95% CI -0.2% to 2.4%). Similar associations were found for black carbon exposure. CONCLUSIONS: Exposure to household air pollution was associated with higher blood pressure and central haemodynamics in older Chinese women, with no associations observed with pulse wave velocity.

Development and Comparison of Air Pollution Exposure Surfaces Derived from On-Road Mobile Monitoring and Short-Term Stationary Sidewalk Measurements.

Land-use regression (LUR) models of air pollutants are frequently developed on the basis of short-term stationary or mobile monitoring approaches, which raises the question of whether these two data collection protocols lead to similar exposure surfaces. In this study, we measured ultrafine particles (UFP) and black carbon (BC) concentrations in Toronto during summer 2016, using two short-term data collection approaches: mobile, involving 3023 road segments sampled on bicycles, and stationary, involving 92 sidewalk locations. We developed four LUR models and exposure surfaces, for the two pollutants and measurement protocols. Coefficients of determination ( R2) varied from 0.434 to 0.525. Various small-scale traffic variables were included in the mobile LUR. Pearson correlation coefficients between the mobile and stationary surfaces were 0.23 for UFP and 0.49 for BC. We also compared the two surfaces using personal exposures from a panel study in Toronto conducted during the same period. The personal exposures differed from the outdoor exposures derived from the combination of GPS information and exposure surfaces. For UFP, the median for personal outdoor exposure was 26 344 part/cm3, while the cycling and stationary surfaces predicted medians of 31 201 and 19 057 part/cm3. Similar trends were observed for BC, with median exposures of 1764 (personal), 1799 (cycling), and 1469 ng/m3 (stationary).

Associations between ambient air pollution and daily mortality in a cohort of congestive heart failure: Case-crossover and nested case-control analyses using a distributed lag nonlinear model.

BACKGROUND: Persons with congestive heart failure may be at higher risk of the acute effects related to daily fluctuations in ambient air pollution. To meet some of the limitations of previous studies using grouped-analysis, we developed a cohort study of persons with congestive heart failure to estimate whether daily non-accidental mortality were associated with spatially-resolved, daily exposures to ambient nitrogen dioxide (NO2) and ozone (O3), and whether these associations were modified according to a series of indicators potentially reflecting complications or worsening of health. METHODS: We constructed the cohort from the linkage of administrative health databases. Daily exposure was assigned from different methods we developed previously to predict spatially-resolved, time-dependent concentrations of ambient NO2 (all year) and O3 (warm season) at participants' residences. We performed two distinct types of analyses: a case-crossover that contrasts the same person at different times, and a nested case-control that contrasts different persons at similar times. We modelled the effects of air pollution and weather (case-crossover only) on mortality using distributed lag nonlinear models over lags 0 to 3 days. We developed from administrative health data a series of indicators that may reflect the underlying construct of "declining health", and used interactions between these indicators and the cross-basis function for air pollutant to assess potential effect modification. RESULTS: The magnitude of the cumulative as well as the lag-specific estimates of association differed in many instances according to the metric of exposure. Using the back-extrapolation method, which is our preferred exposure model, we found for the case-crossover design a cumulative mean percentage changes (MPC) in daily mortality per interquartile increment in NO2 (8.8 ppb) of 3.0% (95% CI: -0.4, 6.6%) and for O3 (16.5 ppb) 3.5% (95% CI: -4.5, 12.1). For O3 there was strong confounding by weather (unadjusted MPC = 7.1%; 95% CI: 1.7, 12.7%). For the nested case-control approach the cumulative MPC for NO2 in daily mortality was 2.9% (95% CI: -0.9, 6.9%) and for O3 7.3% (95% CI: 3.0, 11.9%). We found evidence of effect modification between daily mortality and cumulative NO2 and O3 according to the prescribed dose of furosemide in the nested case-control analysis, but not in the case-crossover analysis. CONCLUSIONS: Mortality in congestive heart failure was associated with exposure to daily ambient NO2 and O3 predicted from a back-extrapolation method using a land use regression model from dense sampling surveys. The methods used to assess exposure can have considerable influence on the estimated acute health effects of the two air pollutants.

The association between the incidence of postmenopausal breast cancer and concentrations at street-level of nitrogen dioxide and ultrafine particles.

BACKGROUND: There is scant information as to whether traffic-related air pollution is associated with the incidence of breast cancer. Nitrogen dioxide (NO2) and ultrafine particles (UFPs, <0.1µm), are two pollutants that capture intra-urban variations in traffic-related air pollution and may also be associated with incidence. METHODS: We conducted a population-based, case-control study of street-level concentrations of NO2 and UFPs and incident postmenopausal breast cancer in Montreal, Canada. Incident cases were identified between 2008 and 2011 from all but one hospital that treated breast cancer in the Montreal area. Population controls were identified from provincial electoral lists of Montreal residents and frequency-matched to cases using 5-year age groups. Concentrations of NO2 and UFPs were estimated using two separate land-use regression models. Exposures were assigned to residential locations at the time of recruitment, and we identified residential histories of women who had lived in these residences for 10 years or more. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression models adjusting for individual-level and ecological covariates. We assessed the functional form of NO2 and UFP exposures using natural cubic splines. RESULTS: We found that the functional form of the response functions between incident postmenopausal breast cancer and concentrations of NO2 and UFPs were consistent with linearity. For NO2, we found increasing risks of breast cancer for all subjects combined and stronger associations when analyses were restricted to those women who had lived at their current address for 10 years or more. Specifically, the OR, adjusted for personal covariates, per increase in the interquartile range (IQR=3.75 ppb) of NO2 was 1.08 (95%CI: 0.92-1.27). For women living in their homes for 10 years or more, the adjusted OR was 1.17 (95%CI: 0.93-1.46; IQR=3.84 ppb); for those not living at that home 10 years before the study, it was 0.93 (95%CI: 0.64, 1.36; IQR=3.65 ppb). For UFPs, the ORs were lower than for NO2, with little evidence of association in any of the models or sub-analyses and little variability in the ORs (about 1.02 for an IQR of ~3500cm-3). On the other hand, we found higher ORs amongst cases with positive oestrogen and progesterone receptor status; namely for NO2, the OR was 1.13 (95%CI: 0.94-1.35) and for UFPs it was 1.05 (95%CI: 0.96-1.14). CONCLUSIONS: Our findings suggest that exposure to ambient NO2 and UFPs may increase the risk of incident postmenopausal breast cancer especially amongst cases with positive oestrogen and progesterone receptor status.

Spatial variations in ambient ultrafine particle concentrations and the risk of incident prostate cancer: A case-control study.

BACKGROUND: Diesel exhaust contains large numbers of ultrafine particles (UFPs, <0.1µm) and is a recognized human carcinogen. However, epidemiological studies have yet to evaluate the relationship between UFPs and cancer incidence. METHODS: We conducted a case-control study of UFPs and incident prostate cancer in Montreal, Canada. Cases were identified from all main Francophone hospitals in the Montreal area between 2005 and 2009. Population controls were identified from provincial electoral lists of French Montreal residents and frequency-matched to cases using 5-year age groups. UFP exposures were estimated using a land use regression model. Exposures were assigned to residential locations at the time of diagnosis/recruitment as well as approximately 10-years earlier to consider potential latency between exposure and disease onset. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated per interquartile range (IQR) increase in UFPs (approximately 4000 particles/cm3) using logistic regression models adjusting for individual-level and ecological covariates. RESULTS: Ambient UFP concentrations were associated with an increased risk of prostate cancer (OR=1.10, 95% CI: 1.01, 1.19) in fully adjusted models when exposures were assigned to residences 10-years prior to diagnosis. This risk estimate increased slightly (OR=1.17, 95% CI; 1.01, 1.35) when modeled as a non-linear natural spline function. A smaller increased risk (OR=1.04, 95% CI: 0.97, 1.11) was observed when exposures were assigned to residences at the time of diagnosis. CONCLUSIONS: Exposure to ambient UFPs may increase the risk of prostate cancer. Future studies are needed to replicate this finding as this is the first study to evaluate this relationship.

Robustness of Land-Use Regression Models Developed from Mobile Air Pollutant Measurements.

Land-use regression (LUR) models are useful for resolving fine scale spatial variations in average air pollutant concentrations across urban areas. With the rise of mobile air pollution campaigns, characterized by short-term monitoring and large spatial extents, it is important to investigate the effects of sampling protocols on the resulting LUR. In this study a mobile lab was used to repeatedly visit a large number of locations (∼1800), defined by road segments, to derive average concentrations across the city of Montreal, Canada. We hypothesize that the robustness of the LUR from these data depends upon how many independent, random times each location is visited (Nvis) and the number of locations (Nloc) used in model development and that these parameters can be optimized. By performing multiple LURs on random sets of locations, we assessed the robustness of the LUR through consistency in adjusted R2 (i.e., coefficient of variation, CV) and in regression coefficients among different models. As Nloc increased, R2adj became less variable; for Nloc = 100 vs Nloc = 300 the CV in R2adj for ultrafine particles decreased from 0.088 to 0.029 and from 0.115 to 0.076 for NO2. The CV in the R2adj also decreased as Nvis increased from 6 to 16; from 0.090 to 0.014 for UFP. As Nloc and Nvis increase, the variability in the coefficient sizes across the different model realizations were also seen to decrease.