Air quality, mortality, and economic benefits of a smoke - free workplace law for non-smoking Ontario bar workers.

We estimated the impact of a smoke-free workplace bylaw on non-smoking bar workers' health in Ontario, Canada. We measured bar workers' urine cotinine before (n = 99) and after (n = 91) a 2004 smoke-free workplace bylaw. Using pharmacokinetic and epidemiological models, we estimated workers' fine-particle (PM2.5 ) air pollution exposure and mortality risks from workplace secondhand smoke (SHS). workers' pre-law geometric mean cotinine was 10.3 ng/ml; post-law dose declined 70% to 3.10 ng/ml and reported work hours of exposure by 90%. Pre-law, 97% of workers' doses exceeded the 90th percentile for Canadians of working age. Pre-law-estimated 8-h average workplace PM2.5 exposure from SHS was 419 µg/m(3) or 'Very Poor' air quality, while outdoor PM2.5 levels averaged 7 µg/m(3) , 'Very Good' air quality by Canadian Air Quality Standards. We estimated that the bar workers' annual mortality rate from workplace SHS exposure was 102 deaths per 100000 persons. This was 2.4 times the occupational disease fatality rate for all Ontario workers. We estimated that half to two-thirds of the 10620 Ontario bar workers were non-smokers. Accordingly, Ontario's smoke-free law saved an estimated 5-7 non-smoking bar workers' lives annually, valued at CA $50 million to $68 million (US $49 million to $66 million).

Assessing the reach of nicotine replacement therapy as a preventive public health measure.

INTRODUCTION: Access to Nicotine Replacement Therapy (NRT) is a key public health intervention to reduce smoking. We assessed prevalence and correlates of use of NRT in Ontario, where NRT is available without prescription. METHODS: Participants were a representative sample of 2262 adult smokers in the Ontario Tobacco Survey cohort. Prospectively measured use of NRT over a 6-month period was reported in relation to smoking behaviour and history, attempts to quit, receipt of other supports for cessation supports and attitudes toward NRT. RESULTS: Overall, 11% of smokers used NRT over the six-month follow-up period. Prevalence was 25% among the 27% of smokers matching clinical guidelines that recommend NRT as a therapeutic option, and low among smokers not trying to quit. CONCLUSION: With increasing accessibility of NRT, further surveillance and research are warranted to determine the impact of the reach and benefits of NRT, considering both the general and targeted smoking populations.

The role of drinking water in the transmission of antimicrobial-resistant E. coli.

To determine whether drinking water contaminated with antimicrobial-resistant E. coli is associated with the carriage of resistant E. coli, selected households sending water samples to Ontario and Alberta laboratories in 2005-2006 were asked to participate in a cross-sectional study. Household members aged ≥12 years were asked to complete a questionnaire and to submit a rectal swab. In 878 individuals, 41% carried a resistant strain of E. coli and 28% carried a multidrug-resistant strain. The risk of carriage of resistant E. coli was 1·26 times higher for users of water contaminated with resistant E. coli. Other risk factors included international travel [prevalence ratio (PR) 1·33], having a child in nappies (PR 1·33), being male (PR 1·33), and frequent handling of raw red meats (PR 1·10). Protecting private water sources (e.g. by improving systems to test and treat them) may help slow the emergence of antimicrobial resistance in E. coli.

Predictive validity and measurement issues in documenting quit intentions in population surveillance studies.

INTRODUCTION: Discrete classification of smokers by intention to quit is desirable in many public health and clinical settings. METHODS: Two methodological studies examine measurement properties of measures of discrete-time intention to quit smoking used in population-based tobacco surveillance surveys: an ecological comparison of rates of positive intention in relation to the form of measure used and a prospective analysis examining predictive validity of self-reported quit intentions using multiple possible points of dichotomization of an ordinal measure of intention to quit. The prospective analysis used a repeated measures design and follow-up to 1 year for 2,047 smokers in the Ontario Tobacco Survey cohort. RESULTS: The estimated percent of smokers intending to quit was significantly higher using the Stages of Change intention measure, relative to another single question measure. Significant dose-response effects were found. The sooner one intended to quit the more likely one was to make an attempt or achieve at least 30 days abstinence in the next 6 months. Intending to quit in a month or later was not associated with cessation during follow-up among respondents without prior attempts. Examination of cutpoints revealed no value, which maximized both positive and negative prediction. Regardless of quit attempt history, greatest predictive validity was found where respondents stated that they had no intention at all. DISCUSSION: Measures of intentions quit smoking in specific time periods and expressed as dichotomies have limited psychometric properties but utility in applied research. Our findings suggest a possible measurement effect warranting caution in comparisons across studies.

Origin and use of the 100 cigarette criterion in tobacco surveys.

Truly global standards and definitions will likely never exist for tobacco control surveillance. One difference across definitions of smoking status is whether or not a lifetime consumption of 100 cigarettes is a necessary criterion for ever and current smoking. Frequently asked questions about this measure demonstrate a need for information on its development and appropriateness in different settings. This commentary attempts to assemble information on the origin and adoption of this measure and provide some critical commentary on its usefulness. The question has been traced to Canadian and American mortality cohort studies from the mid-1950s. From there it has spread to inconsistent use in many settings. To our knowledge, it was not originally (or since) empirically defined as a threshold of exposure related to health consequences or future smoking risk when used in youth. Anecdotal evidence over several decades, however, shows the question has pragmatic utility in self-report data collection. It is a useful, if somewhat arbitrary, screener for "never regular" tobacco use among adults, where never smoking needs to be defined in data collection. Use of the criterion may lower prevalence estimates somewhat. Definitions must always be considered when creating time-trends or international comparisons. There are also circumstances where it is inappropriate to exclude individuals who do not meet this criterion from further data collection, or reports. For research in youth, the criterion typically should be used only with more detailed information about experimentation, but it may be a useful additional indicator of established smoking.

Examining the relationships between job control and health status: a path analysis approach.

OBJECTIVE: To examine the pathways through which job control affects health status; to examine if the effects of job control on health status are attenuated by including other measures associated with lower socioeconomic status, and to examine if the relationship between job control and health status is consistent across socioeconomic status groups. DESIGN: A prospective observational cohort study over eight years (1994-2002). PARTICIPANTS: 4886 Respondents aged 25-60 years, who were non-self-employed labour force participants, working more than 20 hours per week, without physical or mental limitations restricting the type or amount of work they could do at baseline. After longitudinal attrition, the remaining study sample was 3411 (87% of the original study sample who did not die or become pregnant during the survey period). MAIN RESULTS: Low job control in 1994 was associated with worse than expected self-rated health in 2002, both directly and indirectly via a lower physical activity level in 1996. Adjustment for other factors associated with low socioeconomic status did not attenuate these relationships to a large extent. No differences were found in the effects of job control on physical activity or health status between socioeconomic groups (high and low education and high and low household income). CONCLUSIONS: The inclusion of other factors associated with lower socioeconomic status did not attenuate the direct and indirect effects of job control on health status. The finding that low job control is associated with lower physical activity levels deserves further investigation, given the increasing concern about rising levels of obesity in the developed world.

A tale of two time periods: ovarian cancer trends in Ontario.

We assessed population-based trends in incidence and survival rates for epithelial ovarian cancer in Ontario in two time periods. Our population-based study cohort included all women with epithelial ovarian cancer treated initially with abdominal surgery in Ontario for January 1996 through December 2001. Incident surgical cases were documented by hospital contact data and the Ontario Cancer Registry. Patient characteristics (age, for example) were obtained from electronic administrative data records. Regression analyses were used to assess the influence of time period on survival while controlling for age, comorbidity, and other factors associated with this outcome.A total of 3825 women met the inclusion criteria. We found that the age-standardized incidence of ovarian cancer remained stable during 1996-2001. A shift to a younger age at diagnosis was found between the two time periods being compared. The univariate analysis revealed a clear difference in death rate, to which age at diagnosis, Charlson comorbidity score, and treatment period contributed. Earlier time period (p < 0.0001), advancing age (p < 0.0001), higher Charlson score (p < 0.0001), and lower income quartile score (p = 0.03) were significantly associated with poorer survival in the univariate analysis. Younger age, lower Charlson score, and more recent time period of diagnosis and treatment (p < 0.0001) were associated with improved survival in the proportional hazards model.We conclude that age-standardized incidence and mortality rates for ovarian cancer in Ontario have remained stable. For women initially treated with surgery, advances in management have led to an improvement in survival.

Duration and distance of exposure are important predictors of transmission among community contacts of Ontario SARS cases.

We report attack rates and contact-related predictors among community contacts of severe acute respiratory syndrome (SARS) cases from the 2003 Toronto-area outbreak. Community contact data was extracted from public health records for single, well-defined exposures to a SARS case. In total, 8662 community-acquired exposures resulted in 61 probable cases; a crude attack rate of 0.70% [95% confidence interval (CI) 0.54-0.90]. Persons aged 55-69 years were at higher risk of acquiring SARS (1.14%) than those either younger (0.60%) or older (0.70%). In multivariable analysis exposures for at least 30 min at a distance of

Body mass index and mortality in women: follow-up of the Canadian National Breast Screening Study cohort.

OBJECTIVE: The present study was conducted to examine the relationship between obesity and all-cause mortality in women. STUDY DESIGN AND SETTINGS: The subjects were women enrolled from 1980 to 1985 in a Canadian randomized trial, the National Breast Screening Study (NBSS) to evaluate the efficacy of mammographic screening. Mortality was ascertained by record linkage to the Canadian Mortality Data Base. Hazard ratios (HR) for the association between body mass index (BMI) and all-cause mortality were obtained from Cox proportional hazard regression models. RESULTS: During an average follow-up period of 16.5 years, 2566 deaths were identified among the 49 165 women, age 40-59 y at enrollment. The risk of all-cause death increased linearly above a BMI of 22 kg/m(2) and the trend was statistically significant. The HR (and 95% confidence intervals) in the various categories of BMI (kg/m(2)) were: BMI<18.5: 1.12 (0.99-1.25); BMI 18.5-21.9: 1.00 (reference); BMI 22-24.9: 1.15 (1.11-1.18); BMI 25.0-27.9: 1.28 (1.24-1.32); BMI 28.0 -29.9: 1.34 (1.29-1.39); BMI 30.0-34.9: 1.30 (1.25,1.35); and BMI > or =35.0: 1.40 (1.33-1.47). CONCLUSION: This study confirms the association of high BMI with increased all-cause mortality in women.

Socioeconomic status & returning for a second screen in the Ontario breast screening program.

In a retrospective cohort study involving 57902 women initially screened between January 1, 1995 and December 31 1997 by the Ontario Breast Screening Program (OBSP), we examined the relationship between geographically derived socioeconomic status (SES) and returning for a second screen. We controlled for age, rurality, preferred language, initial mammography results, previous mammography history, and referral by a health professional. Although SES was related to returning, rurality was an effect modifier of this relationship, a finding not previously reported. Compared to women in the highest ('richest') quintile, urban women in the first and second quintile were less likely to return; this relationship was not found in rural women. Low SES women, particularly in urban areas, should be specifically targeted to increase their likelihood of re-attendance for breast cancer screening within an organized program.

Outcomes in surgery for ovarian cancer.

OBJECTIVE: Theobjective was to determine the relationship among hospital volume of ovarian cancer surgery,academic status of institution, surgical specialty, and outcomes of care (30-day postoperative mortality, reoperation rate, and overall survival). METHODS: This population-based cohort study included all newly diagnosed ovarian cancer patients treated from 1992 to 1998 in Ontario, Canada. Hospitalization and surgical billing databases were used. Logistic regression was used to evaluate the importance of hospital type, hospital volume, surgical specialty, and surgeon volume of ovarian cancer operations on postoperative mortality, reoperation rates, and survival. RESULTS: Ovarian cancer surgery was performed on 3815 women between April 1992 and March 1998. When adjusted for age, comorbidity, acuity of the operation, and metastatic disease, no factors influenced postoperative mortality. The adjusted relative risk for reoperation within 3 months of the initial surgery showed that patients were less likely to have a repeat operation if the initial operation was done in a high- or intermediate-volume hospital (RR 0.24 95% CI 0.12-0.48, RR 0.29 95% CI 0.20-0.42, respectively), a hospital with a gynecologic oncologist (RR 0.29 95% CI 0.15-0.56), by a gynecologic oncologist (RR 0.04 95% CI 0.01-0.12) or gynecologist (RR 0.37 95% CI 0.21-0.66), or by a high-volume surgeon (RR 0.09 95% CI 0.03-0.23). The adjusted survival was improved if the initial surgery was done by a gynecologic oncologist (HR 0.70 95% CI 0.57-0.85) or gynecologist (HR 0.65 95% CI 0.53-0.79). CONCLUSIONS: There is a relationship between hospital volume and reoperation rate. Institution type only influenced reoperation rate. Statistically significant associations were found between surgical specialty and all three outcome variables. The volume of surgery performed by an individual surgeon only influenced reoperation rate. Our results are preliminary but support the need for further studies examining factors such as stage.

Chiropractic manipulation and stroke: a population-based case-control study.

BACKGROUND AND PURPOSE: Several reports have linked chiropractic manipulation of the neck to dissection or occlusion of the vertebral artery. However, previous studies linking such strokes to neck manipulation consist primarily of uncontrolled case series. We designed a population-based nested case-control study to test the association. METHODS: Hospitalization records were used to identify vertebrobasilar accidents (VBAs) in Ontario, Canada, during 1993-1998. Each of 582 cases was age and sex matched to 4 controls from the Ontario population with no history of stroke at the event date. Public health insurance billing records were used to document use of chiropractic services before the event date. RESULTS: Results for those aged <45 years showed VBA cases to be 5 times more likely than controls to have visited a chiropractor within 1 week of the VBA (95% CI from bootstrapping, 1.32 to 43.87). Additionally, in the younger age group, cases were 5 times as likely to have had >/=3 visits with a cervical diagnosis in the month before the case's VBA date (95% CI from bootstrapping, 1.34 to 18.57). No significant associations were found for those aged >/=45 years. CONCLUSIONS: While our analysis is consistent with a positive association in young adults, potential sources of bias are also discussed. The rarity of VBAs makes this association difficult to study despite high volumes of chiropractic treatment. Because of the popularity of spinal manipulation, high-quality research on both its risks and benefits is recommended.

Impact of normative feedback on problem drinkers: a small-area population study.

OBJECTIVE: As many as one in four adults in North America experiences some problems due to alcohol consumption. Although most of these problem drinkers do not have concerns that are severe enough to merit formal treatment, such drinking has large economic costs and can place the drinker at risk for long-term negative health and social consequences. The present study evaluated a minimal intervention that used normative feedback about population drinking to motivate changes in alcohol use. METHOD: An intervention pamphlet was mailed to over 6,000 households in Toronto, randomized by block from a region containing almost 10,000 households. In the month after the mailing, a general population survey was conducted in the region to assess alcohol use. RESULTS: Respondents from households receiving normative feedback (n = 472) reported significantly lower alcohol use than controls (n = 225), but this effect occurred only among respondents who met an objective criterion for problem drinking and who perceived some risk associated with their drinking. CONCLUSIONS: Viewed from a public health perspective, normative feedback interventions have the potential for a significant payoff because they can be provided at low cost and to problem drinkers who might ordinarily never access any treatment services.

Trends in hormonal management of prostate cancer: a population-based study in Ontario.

OBJECTIVE: To provide a population-based description of current practice in the use of hormonal management of prostate cancer. DESIGN,SETTING & PARTICIPANTS: All men in Ontario, Canada, age 65 and older, with confirmed prostate cancer starting maintained hormonal therapy, from July 1992 through December 1998 (11,435 patients). Data sources included the provincial drug benefit plan, hospital services data, and Ontario Cancer Registry. OUTCOME MEASURES: Rates and trends in the use of: surgical or medical castration; total androgen blockade (TAB); and monotherapies based on steroidal or nonsteroidal antiandrogens. RESULTS: In 5.5 years, use of 'standard' therapy based on surgical or medical castration alone dropped from 36% to 26% of patients, while the use of TAB doubled from 22% to 41%. Approximately 15% of patients received nonsteroidal antiandrogens without evidence of therapy aimed at central androgen blockade. Marked regional differences were observed and not explained by patient age or practitioner specialty. CONCLUSIONS: New hormonal therapies for prostate cancer have implications in terms of disease control, patient survival, side effects, and costs. Rapid growth in prescribing of antiandrogens may represent an unnecessary expense for public or private payers, and observed regional differences likely reflect lack of consensus on the relative merit of TAB. Patients and practitioners must have current information on the advantages and disadvantages of different therapeutic options, and quality-of life, particularly with respect to emerging drug therapies.

Alcohol and breast cancer mortality in a cohort study.

Available epidemiological evidence indicates that alcohol intake is associated with a higher risk of developing breast cancer. Plausible biological pathways include its effect on levels of estrogens, cell membrane integrity and cell-to-cell communication, inhibition of DNA repair, and congener effect. The present study evaluated the impact of alcohol on mortality from breast cancer, an area with relatively few studies in the literature. The subjects were participants in a Canadian prospective cohort study, the National Breast Screening Study (NBSS). Women were enrolled in the cohort from 1980 to 1985 to evaluate the efficacy of mammographic screening. Information on usual diet and alcohol intake at enrolment and other epidemiological variables was collected by means of a mailed, self-administered questionnaire. Mortality from breast cancer during follow- up to 31 December, 1993 was ascertained by record linkage to the Canadian Mortality Data Base maintained by Statistics Canada. During the follow-up period of 1980-1993 (average 10.3 years), 223 deaths from breast cancer were identified for this analysis. The hazard ratios for the risk of death from breast cancer increased with intakes of total alcohol of 10-20 g/day (1.039, 1.009-1.071) and > 20 g/day ( 1.063, 1.029-1.098). This increase was contributed largely by the intake of wine, a 15% increase in risk at intakes higher than 10 g/day of alcohol from wine. Alcohol from spirits was associated with a small decrease in risk of death (hazard ratio at 10g/day, 0.945, 0.915-0.976). The effect of alcohol from beer was not significant in the two categories studied. Although our results were statistically significant, the magnitude of the change in risk was small.

Measuring alcohol-related harm: test-retest reliability of a popular measure.

This study assessed the test-retest reliability of a measure of alcohol-related harm commonly used in cross-sectional surveys. Sixty-four respondents of a 1995 telephone survey participated in a second interview 3 to 5 months after the survey. Drinking status and average volume of alcohol consumed proved to be highly reliable. For the lifetime harm scale, correlation was satisfactory, and reliability fell just short of satisfactory agreement (kappa = 0.716). For a score of alcohol-related harm in the past year, poor reliability was shown (kappa = 0.484). Future research must place greater emphasis on objective indicators and on validation of the measures used.

Low-risk drinking guidelines: the scientific evidence.

In 1997 the Addiction Research Foundation of Ontario and Canadian Centre on Substance Abuse released updated guidelines for low-risk alcohol consumption. This paper presents the scientific rationale behind this statement. Important comprehensive overviews on the consequences of alcohol use were studied. Formal meta-analyses on morbidity and mortality were examined wherever possible. Individual elements from similar guidelines were investigated for their scientific foundation. Limited original analyses defined risk levels by average weekly consumption. The evidence reviewed demonstrated that placing limits on both daily intake and cumulative intake over the typical week is justifiable for the prevention of important causes of morbidity and mortality. Gender-specific limits on weekly consumption were also indicated. In these updated guidelines intended for primary prevention, days of abstinence are not necessarily recommended. Intoxication should be avoided and abstinence is sometimes advisable. Available evidence does not strongly favour one alcoholic beverage over another for cardiovascular health benefits.

Do Ontarians drink in moderation? a baseline assessment against Canadian low risk drinking guidelines.

We used the 1997 Ontario Drug Monitor, a population-based, random-digit dialing survey of 2,776 adults, to obtain a baseline assessment of alcohol drinking by Ontarians against the 1997 low-risk drinking guidelines of the Addiction Research Foundation and the Canadian Centre on Substance Abuse. Average weekly alcohol consumption and the frequency of exceeding the daily limit, estimated using the graduated frequency scale, were determined for the population overall, and by sex and age group (18-44 and 45+ years). Most Ontarians drank alcohol in a pattern associated with a low risk of health consequences. About 10% of women and 25% of men drank in a style associated with some increase in acute or long-term risk. Younger men were most likely to drink in a risky pattern. Most drinkers of middle age or older, for whom cardiovascular disease is a significant health risk, consumed alcohol in a pattern associated with cardiovascular benefit.