Treating Overactive Bladder in Older Patients with a Combination of Mirabegron and Solifenacin: A Prespecified Analysis from the BESIDE Study.

BACKGROUND: The BESIDE study demonstrated that combination therapy (mirabegron and solifenacin 5mg) improved overactive bladder symptoms versus solifenacin 5mg or 10mg, and was well tolerated. OBJECTIVE: To ensure efficacy and safety is maintained in older patients (>65 yr), who usually experience greater symptom severity and comorbidities, a prespecified subanalysis stratified by age group was conducted. DESIGN, SETTING, AND PARTICIPANTS: Patients remaining incontinent (≥1 episode during 3-d diary) following 4-wk single-blind daily solifenacin 5mg were randomized 1:1:1 to a daily double-blind combination (solifenacin 5mg and mirabegron 25mg, increased to 50mg at wk 4), solifenacin 5mg or 10mg for 12 wk. Four cohorts stratified by age (<65 yr, ≥65 yr and < 75 yr, ≥75 yr) were investigated. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Efficacy assessments: change from baseline to end of treatment in average daily incontinence (primary) and micturition frequency (key secondary), number of incontinence episodes during the 3-d diary (key secondary), and change from baseline in average daily urgency and urgency incontinence episodes. Safety included treatment-emergent adverse events and vital signs. RESULTS AND LIMITATIONS: Full analysis set included 2110 patients: 30.9% aged ≥65 yr and 8.9% aged ≥75 yr. At the end of treatment, daily, and 3-d incontinence daily micturitions, urgency, and urgency incontinence, were improved in each treatment group and age group; the largest reductions were observed with combination in each age cohort. There were no notable differences in vital signs or the incidence of treatment-emergent adverse events between treatment and age groups, with the exception of dry mouth, which was highest with solifenacin 10mg. CONCLUSIONS: Efficacy and safety in the overall population is maintained in older (≥65 yr) and elderly (≥75 yr) patients treated with a combination of solifenacin and mirabegron, or solifenacin monotherapy; irrespective of age, combination was associated with the greatest improvement in overactive bladder symptoms. PATIENT SUMMARY: This study investigated the effectiveness and safety of a combination of two different treatments (mirabegron 50mg and solifenacin 5mg) or solifenacin (5mg or 10mg) alone in patients aged <65 yr or ≥65 yr, and <75 yr or ≥75 yr with overactive bladder. Symptoms of overactive bladder, such as the urgent need to visit the toilet, incontinence, and frequent urination, were improved with all treatments regardless of the patient's age, but combination treatment demonstrated the greatest benefit, and was well tolerated.

An Exploratory Study in Healthy Male Subjects of the Mechanism of Mirabegron-Induced Cardiovascular Effects.

To explore the role of ß1 -adrenoceptors (ARs) in the heart rate response to the selective ß3 -adrenoceptor agonist mirabegron, 12 young male volunteers received single oral doses of the nonselective ß1/2 -AR antagonist propranolol (160 mg), the selective ß1 -AR antagonist bisoprolol (10 mg), or placebo on days 1 and 5 of each period in a 3-period crossover study. On day 5, dosing was followed by a supratherapeutic dose of mirabegron (200 mg). Vital signs, impedance cardiography, and plasma renin activity were collected. Mirabegron increased heart rate and systolic blood pressure and reduced stroke volume, whereas cardiac output and diastolic blood pressure were unaffected. Mirabegron-induced changes were attenuated by propranolol and bisoprolol. The data indicate that mirabegron has a positive chronotropic effect at supratherapeutic concentrations, which is at least partly mediated by stimulation of ß1 -AR.

Mirabegron as Add-On Treatment to Solifenacin in Patients with Incontinent Overactive Bladder and an Inadequate Response to Solifenacin Monotherapy: Responder Analyses and Patient-Reported Outcomes from the BESIDE Study [corrected].

PURPOSE: We investigated improvements in overactive bladder and patient reported outcomes in patients with overactive bladder and refractory incontinence treated with mirabegron 50 mg plus solifenacin 5 mg vs solifenacin 5 or 10 mg. MATERIALS AND METHODS: Patients with overactive bladder who were incontinent despite 4 weeks of single-blind daily solifenacin 5 mg were randomized 1:1:1 to a double-blind daily combination of mirabegron 50 mg/solifenacin 5 mg, or solifenacin 5 or 10 mg for 12 weeks. The mirabegron dose was increased from 25 to 50 mg after week 4. Symptom bother, health related quality of life and patient perception of bladder condition were assessed by OAB-q (Overactive Bladder Questionnaire) and the PPBC (Patient Perception of Bladder Condition) questionnaire, respectively. Responder rates were based on a 50% reduction in daily incontinence, zero incontinence episodes and fewer than 8 micturitions per 24 hours with minimal important differences in OAB-q and PPBC. RESULTS: Overall 2,174 patients with a median age of 59 years were randomized, including 727 to the combination, 728 to solifenacin 5 mg and 719 to solifenacin 10 mg. Symptom bother, total health related quality of life and its subscales (coping, concern and social), and PPBC were significantly improved with combination vs solifenacin monotherapy (p <0.05). The odds of achieving clinically meaningful improvements in incontinence, micturition frequency, symptom bother, health related quality of life and PPBC were significantly higher for combination than solifenacin monotherapy. The odds of becoming continent was 47% and 28% higher for combination vs solifenacin 5 and 10 mg (OR 1.47, 95% CI 1.17-1.84, p = 0.001 and OR 1.28; 95% CI 1.02-1.61, p = 0.033, respectively). CONCLUSIONS: Significantly more patients on the combination achieved clinically meaningful improvements in incontinence and micturition frequency. Improvements were accompanied by similar improvements in PPBC, symptom bother and health related quality of life.

Efficacy and Safety of Mirabegron Add-on Therapy to Solifenacin in Incontinent Overactive Bladder Patients with an Inadequate Response to Initial 4-Week Solifenacin Monotherapy: A Randomised Double-blind Multicentre Phase 3B Study (BESIDE).

BACKGROUND: Incontinence has a greater detrimental effect on quality of life than other symptoms of overactive bladder (OAB) and is often difficult to treat with antimuscarinic monotherapy. OBJECTIVE: To evaluate the efficacy and the safety and tolerability of combination (solifenacin 5mg and mirabegron 50mg) versus solifenacin 5 or 10mg in OAB patients remaining incontinent after 4 wk of solifenacin 5mg. DESIGN, SETTING, AND PARTICIPANTS: OAB patients remaining incontinent despite daily solifenacin 5mg during 4-wk single-blind run-in were randomised 1:1:1 to double-blind daily combination or solifenacin 5 or 10mg for 12 wk. Patients receiving the combination were initiated on mirabegron 25mg increasing to 50mg after week 4. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary end point was a change from baseline to end of treatment (EOT) in the mean number of incontinence episodes per 24h (stratified rank analysis of covariance [ANCOVA]). Key secondary end points were a change from baseline to EOT in the mean number of micturitions per 24h (ANCOVA) and number of incontinence episodes noted in a 3-d diary at EOT (mixed-effects Poisson regression). A trial (BESIDE) comparing combination treatment (solifenacin plus mirabegron) with one treatment alone (solifenacin) tested the superiority of combination versus solifenacin 5mg, noninferiority (and potential superiority) of combination versus solifenacin 10mg (key secondary end points), and the safety and tolerability of combination therapy versus solifenacin monotherapy. RESULTS AND LIMITATIONS: A total of 2174 patients were randomised to combination (n=727), solifenacin 5mg (n=728), or solifenacin 10mg (n=719). At EOT, combination was superior to solifenacin 5mg, with significant improvements in daily incontinence (p=0.001), daily micturitions (p<0.001), and incontinence noted in a 3-d diary (p=0.014). Combination was noninferior to solifenacin 10mg for key secondary end points and superior to solifenacin 10mg for improving daily micturitions. All treatments were well tolerated. CONCLUSIONS: Adding mirabegron 50mg to solifenacin 5mg further improved OAB symptoms versus solifenacin 5 or 10mg, and it was well tolerated in OAB patients remaining incontinent after initial solifenacin 5mg. PATIENT SUMMARY: In this 12-wk study, overactive bladder patients who remained incontinent despite initial solifenacin 5mg treatment received additional treatment with mirabegron 50mg. Combining mirabegron 50mg with solifenacin 5mg was superior to solifenacin 5mg alone in improving symptoms of incontinence and frequent urination, and it was well tolerated. TRIAL REGISTRATION: ClinicalTrials.gov NCT01908829.

A phase III, randomized, double-blind, parallel-group, placebo-controlled, multicentre study to assess the efficacy and safety of the ß3 adrenoceptor agonist, mirabegron, in patients with symptoms of overactive bladder.

OBJECTIVE: To assess the efficacy and tolerability of mirabegron 25 mg and 50 mg once-daily vs placebo in patients with overactive bladder (OAB). MATERIALS AND METHODS: Patients ≥18 years with OAB symptoms were recruited to a 2-week, single-blind, placebo run-in. Those with ≥8 micturitions per 24 hours and ≥3 urgency episodes were randomized 1:1:1 to once-daily mirabegron 25 mg or 50 mg, or placebo for 12 weeks. Primary endpoints were changes to final visit in mean number of incontinence episodes and micturitions per 24 hours. Key secondary endpoints were changes to final visit in mean volume voided or micturition, change to week 4 in mean number of incontinence episodes and micturitions per 24 hours, changes to final visit in mean level of urgency, number of urgency incontinence episodes, and urgency (grade 3 or 4) episodes per 24 hours. Patient-reported outcomes were assessed using the OAB-questionnaire, Patient Perception of Bladder Condition, and Treatment-Satisfaction-Visual Analog Scale. RESULTS: Both mirabegron groups demonstrated statistically significant improvements in coprimary endpoints vs placebo. Mirabegron 50 mg demonstrated significantly greater improvements vs placebo in the following: change to final visit in mean volume voided per micturition and change to week 4 in mean number of incontinence episodes per 24 hours. Statistically significant improvements vs placebo were demonstrated by mirabegron 50 mg in all patient-reported outcome scales with no increase in the incidence of treatment-emergent adverse events vs placebo. CONCLUSION: Mirabegron 25 mg and 50 mg were associated with significant improvements in efficacy measures of incontinence episodes and micturition frequency. Mirabegron was well tolerated vs placebo.

The influence of improved air quality on mortality risks in Erfurt, Germany.

Around the world, daily variations in ambient air pollution have been consistently associated with variations in daily mortality. The aim of the study presented here was to assess the effects of ambient air pollution on daily mortality during a period of tremendous changes in air quality in the city of Erfurt, in eastern Germany, from October 1991 to March 2002. Data on particle size distributions were obtained from September 1995 to March 2002 at a research monitoring station. For particles from 0.01 microm to 2.5 microm in diameter, number concentrations (NCs)* and mass concentrations (MCs) were calculated. Particles with diameters less than or equal to 0.10 microm are defined as ultrafine particles (UFP). Data on the gaseous pollutants NO2, CO, SO2, and O3 and on PM10 (particulate matter [PM] with aerodynamic diameter less than or equal to 10 microm) were obtained from a government air-monitoring station. Data on changes in energy consumption, car fleet composition, and population were collected from local authorities. Death certificates of persons living in and dying in Erfurt were abstracted, and daily mortality counts were calculated. Poisson regression models were used to analyze the data, applying penalized splines (also known as P-splines) to model nonlinear relationships in the confounders. Model selection was done without air pollutants in the models, based on a combination of goodness-of-fit criteria and avoidance of autocorrelation in error terms. Final models included P-splines of time trend, meteorologic data, and influenza epidemics as well as day of the week with an indicator variable. Results are presented as change per interquartile range (IQR), i.e., change in the relative risk of mortality associated with a change in the concentration from the 25th to the 75th percentile of a given pollutant. Air pollutants were considered both as linear terms and as P-splines to assess the exposure-response functions. Changes in effect estimates over time were calculated using fully Bayesian time-varying coefficient models. This method was selected over four other approaches tested in simulation studies. Air-pollution concentrations decreased substantially in Erfurt during the decade under observation. The strongest changes were observed for SO2, for which annual concentrations decreased from 64 microg/m3 in 1992 to 4 microg/m3 in 2001. Concentrations of PM10, PM2.5 (particulate matter with aerodynamic diameter less than or equal to 2.5 microm), and CO decreased by more than 50%. NO2, O3, and ultrafine particles also decreased, though to a lesser extent. Based on visual inspection of the data on the changes in ambient air-pollution concentrations during the study period, we defined three study subperiods: A first subperiod from 1991 to 1995; a second, transitional subperiod from 1995 to 1998; and a third subperiod from 1998 to 2002. Generally, air-pollution concentrations decreased substantially from the first subperiod to the second, and some additional decreases occurred from the second subperiod to the third. During the second, transitional subperiod, natural gas replaced coal as the main energy source in Erfurt. In addition, the number of cars with catalytic converters increased over time, as did the number of cars in general. To facilitate the interpretation of the results, we organized the air pollutants into four groups: (1) NO2, CO, and ultrafine particles, (2) PM10 and PM2.5, (3) SO2, and (4) O3. We observed a 1.6% increased risk for daily mortality (CI, -0.4% to 3.5%) for an increase of 19.7 microg/m3 in NO2 (lag day 3), a 1.9% increased risk (CI, 0.2%-3.6%) for an increase of 0.48 mg/m3 in CO (lag day 4), and a 2.9% increased risk (CI, 0.3%-5.5%) for an increase of 9743/cm3 in ultrafine particles (lag day 4). No consistent associations were observed for PM10, PM2.5, or SO2. For O3, a 4.6% increased risk for daily mortality (CI, 1.1%-8.3%) was associated with a 43.8 microg/m3 maximum 8-hr concentration of O3 per day (lag day 2). For all four pollutants, exposure-response functions suggested no deviation from linearity. However, in time-varying models the strongest associations were observed for NO2, CO, and ultrafine particles during the transition subperiod, from 1995 to 1998, when O3 concentrations were lowest. Changes in source characteristics or ambient air-pollution concentrations were not able to explain these observations in a straightforward manner. However, the observations suggested that changes such as the introduction of three-way catalytic converters in cars and the substitution natural gas for coal might have been beneficial. Overall we concluded that: 1. Economic and political changes and the adoption of new technologies in eastern Germany resulted in distinct improvements in ambient air quality; 2. Urban air pollution in Erfurt changed within one decade from the eastern mixture toward that of western Europe ("western mixture"), which is dominated by concentrations of NOx, O3, fine particles, and ultrafine particles with low concentrations of SO2; 3. There was an association between daily mortality and ultrafine particles and combustion-related gases (lag days 3 or 4); 4. Ultrafine particles seemed to be the best pollution indicator and to point to the role of local combustion in the pollution mixture; 5. Regression coefficients showed variation over time for NO2, CO, ultrafine particles, and O3 that could not be explained by nonlinearity in the exposure-response functions; 6. Mortality associated with pollution was lower at the end of the 1990s than during the 1990s, except for mortality associated with O3; and 7. Mortality associated with pollution was strongest in the second, transitional subperiod, from 1995 to 1998, when changes in source characteristics had taken place but the benefits of improved ambient air quality had not yet been completely achieved.

Short-term mortality rates during a decade of improved air quality in Erfurt, Germany.

BACKGROUND: Numerous studies have shown associations between ambient air pollution and daily mortality. OBJECTIVES: Our goal was to investigate the association of ambient air pollution and daily mortality in Erfurt, Germany, over a 10.5-year period after the German unification, when air quality improved. METHODS: We obtained daily mortality counts and data on mass concentrations of particulate matter (PM)<10 microm in aerodynamic diameter (PM10), gaseous pollutants, and meteorology in Erfurt between October 1991 and March 2002. We obtained ultrafine particle number concentrations (UFP) and mass concentrations of PM<2.5 microm in aerodynamic diameter (PM2.5) from September 1995 to March 2002. We analyzed the data using semiparametric Poisson regression models adjusting for trend, seasonality, influenza epidemics, day of the week, and meteorology. We evaluated cumulative associations between air pollution and mortality using polynomial distributed lag (PDL) models and multiday moving averages of air pollutants. We evaluated changes in the associations over time in time-varying coefficient models. RESULTS: Air pollution concentrations decreased over the study period. Cumulative exposure to UFP was associated with increased mortality. An interquartile range (IQR) increase in the 15-day cumulative mean UFP of 7,649 cm(-3) was associated with a relative risk (RR) of 1.060 [95% confidence interval (CI), 1.008-1.114] for PDL models and an RR/IQR of 1.055 (95% CI, 1.011-1.101) for moving averages. RRs decreased from the mid-1990s to the late 1990s. CONCLUSION: Results indicate an elevated mortality risk from short-term exposure to UFP. They further suggest that RRs for short-term associations of air pollution decreased as pollution control measures were implemented in Eastern Germany.

Source apportionment of ambient fine particle size distribution using positive matrix factorization in Erfurt, Germany.

Particle size distribution data collected between September 1997 and August 2001 in Erfurt, Germany were used to investigate the sources of ambient particulate matter by positive matrix factorization (PMF). A total of 29,313 hourly averaged particle size distribution measurements covering the size range of 0.01 to 3.0 microm were included in the analysis. The particle number concentrations (cm(-3)) for the 9 channels in the ultrafine range, and mass concentrations (ng m(-3)) for the 41 size bins in the accumulation mode and particle up to 3 microm in aerodynamic diameter were used in the PMF. The analysis was performed separately for each season. Additional analyses were performed including calculations of the correlations of factor contributions with gaseous pollutants (O(3), NO, NO(2), CO and SO(2)) and particle composition data (sulfate, organic carbon and elemental carbon), estimating the contributions of each factor to the total number and mass concentration, identifying the directional locations of the sources using the conditional probability function, and examining the diurnal patterns of factor scores. These results were used to assist in the interpretation of the factors. Five factors representing particles from airborne soil, ultrafine particles from local traffic, secondary aerosols from local fuel combustion, particles from remote traffic sources, and secondary aerosols from multiple sources were identified in all seasons.

Ambient source-specific particles are associated with prolonged repolarization and increased levels of inflammation in male coronary artery disease patients.

Ambient particulate air pollution has been associated with altered cardiac function and systemic inflammation. We reported repolarization changes and variations in markers of inflammation in association with ambient particulate exposure in a panel of male coronary artery disease (CAD) patients. The objective of this analysis was to identify the specific sources associated with these effects. A panel of male CAD patients participated in 12 clinical visits in Erfurt, Germany. We used 56 patients' 5min ECG recordings for the analysis of repolarization parameters QT interval and T wave amplitude, and 57 patients' plasma samples to determine the biomarkers von Willebrand factor (vWF) and C-reactive protein (CRP). Linear and logistic regression models were used to analyze the associations between five particle source factors (airborne soil, local traffic-related ultrafine particles, combustion-generated aerosols, diesel traffic-related particles, and secondary aerosols) and these health parameters adjusting for trend, weekday and meteorological variables. An increase in QT interval and a decrease in T wave amplitude were observed in association with traffic-related particles exposure during 0-23h before the ECG recordings. The inflammatory marker vWF increased in association with both traffic-related particles and combustion-generated aerosols at different exposure lags. All source particles had positive associations with CRP levels above the 90th percentile (8.5mg/l). These results suggest that traffic-related and combustion-generated particles show stronger adverse health impact with regard to cardiac effects, and that particles from different sources induce an acute phase response in these patients.

Semi volatile organic compounds in ambient PM2.5. Seasonal trends and daily resolved source contributions.

Concentrations of ambient semivolatile organic compounds (SVOC) in the PM2.5 fraction of Augsburg, Germany, have been monitored on a daily basis from January 2003 through December 2004. Samples were taken in a large garden in the city center. Quantitative analysis of n-alkanes, alkanones, alkanoic acid methylesters, long chain linear alkyl benzenes and toluenes, hopanes, polycyclic aromatic hydrocarbons (PAH) and oxidized PAH, and some abietan type diterpenes was done. All compounds showed distinct seasonal variations in concentration. Most compounds showed highest concentrations during the cold seasons, but some n-alkanones and 6,10,14-trimethylpentadecanone showed maximum concentration during summer. Changes in patterns between and within compound classes were obvious, e.g., the hopane pattern exhibited a strong seasonal variation. The main source related contributions to changes observed were discussed. Using positive matrix factorization (PMF) for the statistical investigation of the data set, five factors have been separated. These factors are dominated by the pattern of single sources or groups of similar sources: factor 1, lubricating oil; factor 2, emissions of unburned diesel and heating oil consumption; factor 3, wood combustion; factor 4, brown coal combustion; and factor 5, biogenic emissions and transport components. Like the SVOC, the factors showed strong seasonality with highest values in winter for factors 1-4 and in summer for factor 5.

Daily mortality and particulate matter in different size classes in Erfurt, Germany.

The link between elevated concentrations of ambient particulate matter (PM) and increased mortality has been investigated in numerous studies. Here we analyzed the role of different particle size fractions with respect to total and cardio-respiratory mortality in Erfurt, Germany, between 1995 and 2001. Number concentrations (NC) of PM were measured using an aerosol spectrometer consisting of a Differential Mobility Particle Sizer and a Laser Aerosol Spectrometer to characterize particles between 0.01 and 0.5 and between 0.1 and 2.5 microm, respectively. We derived daily means of particle NC for ultrafine (0.01-0.1 microm) and for fine particles (0.01-2.5 microm). Assuming spherical particles of a constant density, we estimated the mass concentrations (MC) of particles in these size ranges. Concurrently, data on daily total and cardio-respiratory death counts were obtained from local health authorities. The data were analyzed using Poisson Generalized Additive Models adjusting for trend, seasonality, influenza epidemics, day of the week, and meteorology using smooth functions or indicator variables. We found statistically significant associations between elevated ultrafine particle (UFP; diameter: 0.01-0.1 microm) NC and total as well as cardio-respiratory mortality, each with a 4 days lag. The relative mortality risk (RR) for a 9748 cm(-3) increase in UFP NC was RR=1.029 and its 95% confidence interval (CI)=1.003-1.055 for total mortality. For cardio-respiratory mortality we found: RR=1.031, 95% CI: 1.003-1.060. No association between fine particle MC and mortality was found. This study shows that UFP, representing fresh combustion particles, may be an important component of urban air pollution associated with health effects.

Can we identify sources of fine particles responsible for exercise-induced ischemia on days with elevated air pollution? The ULTRA study.

Epidemiologic studies have shown that ambient particulate matter (PM) has adverse effects on cardiovascular health. Effective mitigation of the health effects requires identification of the most harmful PM sources. The objective of our study was to evaluate relative effects of fine PM [aerodynamic diameter0.1 mV, with odds ratios at 2-day lag of 1.53 [95% confidence interval (CI), 1.19-1.97] and 1.11 (95% CI, 1.02-1.20) per 1 microg/m3, respectively. In multipollutant models, where we used indicator elements for sources instead of source-specific PM2.5, only absorbance (elemental carbon), an indicator of local traffic and other combustion, was associated with ST segment depressions. Our results suggest that the PM fraction originating from combustion processes, notably traffic, exacerbates ischemic heart diseases associated with PM mass.

PM source apportionment and health effects. 3. Investigation of inter-method variations in associations between estimated source contributions of PM2.5 and daily mortality in Phoenix, AZ.

As part of an EPA-sponsored workshop to investigate the use of source apportionment in health effects analyses, the associations between the participant's estimated source contributions of PM(2.5) for Phoenix, AZ for the period from 1995-1997 and cardiovascular and total nonaccidental mortality were analyzed using Poisson generalized linear models (GLM). The base model controlled for extreme temperatures, relative humidity, day of week, and time trends using natural spline smoothers. The same mortality model was applied to all of the apportionment results to provide a consistent comparison across source components and investigators/methods. Of the apportioned anthropogenic PM(2.5) source categories, secondary sulfate, traffic, and copper smelter-derived particles were most consistently associated with cardiovascular mortality. The sources with the largest cardiovascular mortality effect size were secondary sulfate (median estimate=16.0% per 5th-to-95th percentile increment at lag 0 day among eight investigators/methods) and traffic (median estimate=13.2% per 5th-to-95th percentile increment at lag 1 day among nine investigators/methods). For total mortality, the associations were weaker. Sea salt was also found to be associated with both total and cardiovascular mortality, but at 5 days lag. Fine particle soil and biomass burning factors were not associated with increased risks. Variations in the maximum effect lag varied by source category suggesting that past analyses considering only single lags of PM(2.5) may have underestimated health impact contributions at different lags. Further research is needed on the possibility that different PM(2.5) source components may have different effect lag structure. There was considerable consistency in the health effects results across source apportionments in their effect estimates and their lag structures. Variations in results across investigators/methods were small compared to the variations across source categories. These results indicate reproducibility of source apportionment results across investigative groups and support applicability of these methods to effects studies. However, future research will also need to investigate a number of other important issues including accuracy of results.

PM source apportionment and health effects: 1. Intercomparison of source apportionment results.

During the past three decades, receptor models have been used to identify and apportion ambient concentrations to sources. A number of groups are employing these methods to provide input into air quality management planning. A workshop has explored the use of resolved source contributions in health effects models. Multiple groups have analyzed particulate composition data sets from Washington, DC and Phoenix, AZ. Similar source profiles were extracted from these data sets by the investigators using different factor analysis methods. There was good agreement among the major resolved source types. Crustal (soil), sulfate, oil, and salt were the sources that were most unambiguously identified (generally highest correlation across the sites). Traffic and vegetative burning showed considerable variability among the results with variability in the ability of the methods to partition the motor vehicle contributions between gasoline and diesel vehicles. However, if the total motor vehicle contributions are estimated, good correspondence was obtained among the results. The source impacts were especially similar across various analyses for the larger mass contributors (e.g., in Washington, secondary sulfate SE=7% and 11% for traffic; in Phoenix, secondary sulfate SE=17% and 7% for traffic). Especially important for time-series health effects assessment, the source-specific impacts were found to be highly correlated across analysis methods/researchers for the major components (e.g., mean analysis to analysis correlation, r>0.9 for traffic and secondary sulfates in Phoenix and for traffic and secondary nitrates in Washington. The sulfate mean r value is >0.75 in Washington.). Overall, although these intercomparisons suggest areas where further research is needed (e.g., better division of traffic emissions between diesel and gasoline vehicles), they provide support the contention that PM(2.5) mass source apportionment results are consistent across users and methods, and that today's source apportionment methods are robust enough for application to PM(2.5) health effects assessments.

Workgroup report: workshop on source apportionment of particulate matter health effects--intercomparison of results and implications.

Although the association between exposure to ambient fine particulate matter with aerodynamic diameter < 2.5 microm (PM2.5) and human mortality is well established, the most responsible particle types/sources are not yet certain. In May 2003, the U.S. Environmental Protection Agency's Particulate Matter Centers Program sponsored the Workshop on the Source Apportionment of PM Health Effects. The goal was to evaluate the consistency of the various source apportionment methods in assessing source contributions to daily PM2.5 mass-mortality associations. Seven research institutions, using varying methods, participated in the estimation of source apportionments of PM2.5 mass samples collected in Washington, DC, and Phoenix, Arizona, USA. Apportionments were evaluated for their respective associations with mortality using Poisson regressions, allowing a comparative assessment of the extent to which variations in the apportionments contributed to variability in the source-specific mortality results. The various research groups generally identified the same major source types, each with similar elemental makeups. Intergroup correlation analyses indicated that soil-, sulfate-, residual oil-, and salt-associated mass were most unambiguously identified by various methods, whereas vegetative burning and traffic were less consistent. Aggregate source-specific mortality relative risk (RR) estimate confidence intervals overlapped each other, but the sulfate-related PM2.5 component was most consistently significant across analyses in these cities. Analyses indicated that source types were a significant predictor of RR, whereas apportionment group differences were not. Variations in the source apportionments added only some 15% to the mortality regression uncertainties. These results provide supportive evidence that existing PM2.5 source apportionment methods can be used to derive reliable insights into the source components that contribute to PM2.5 health effects.