Wellness programs: a review of the evidence

OBJECTIVE: To review studies that have examined an association between wellness programs and improvements in quality of life and to assess the strength of the scientific evidence. DATA SOURCES: A MEDLINE search was constructed with the following medical subject headings: "psychoneuroimmunology," "chronic disease" and "health promotion," "chronic disease" and "health behaviour," "relaxation techniques," "music therapy," "laughter," "anger," "mediation" and "behavioural medicine." Searches using the text words "wellness" and "wellness program" were also carried out. References from the primary articles identified in the search and contemporary writing on wellness were also considered. STUDY SELECTION: Selection was limited to randomized controlled trials or prospective studies published in English that involved human subjects and that took place between 1980 and 1996. All studies with an intervention aimed at promoting wellness and measuring outcomes were included, except studies of patients with cancer and HIV and studies of health promotion programs in the workplace. Of the 1082 references initially identified, 11 met the criteria for inclusion in the critical appraisal. DATA EXTRACTION: The following information was extracted from the 11 studies: characteristics of the study population, number of participants (and number followed to completion), length of follow-up, type of intervention, outcome measures and results. All 11 studies were assessed for the quality of their evidence. DATA SYNTHESIS: All studies reported some positive outcomes following the intervention in question, although many had limitations precluding applicability of the results to a wider population. CONCLUSIONS: Despite the suggested benefit associated with wellness programs, the evidence was inconclusive. Whether the composition of the target group or the type of intervention has a role in determining outcomes is unknown. Although trends suggest that wellness programs may be cost-effective, further research is needed for confirmation.     

Clinical features and treatment of obstructive sleep apnea.

OBJECTIVE: To review the clinical features and treatment of obstructive sleep apnea (OSA). DATA SOURCE AND SELECTION: All articles on OSA published in French and English between 1970 and 1990 and indexed in Index Medicus were reviewed. Studies addressing the epidemiologic features and clinical aspects of OSA were selected, and special emphasis was given to articles reporting the effects of treatment on morbidity and mortality rates. MAIN RESULTS: OSA is characterized by episodes of upper airway obstruction during sleep that result in repetitive hypoxemia and sleep disruption. OSA leads to various neuropsychologic and cardiovascular complications, including daytime hypersomnolence, cognitive impairment, systemic and pulmonary hypertension and cardiac arrhythmias. There is suggestive evidence that the death rate among affected people is increased. The true incidence of OSA is unknown, but estimates have varied from 1% upwards among men. The current treatment with the greatest overall effectiveness and acceptability is nasal continuous positive airway pressure. CONCLUSION: This common, readily treatable disorder is associated with serious complications and therefore must be widely recognized by health professionals.     

The effects of clinical practice guidelines on patient outcomes in primary care: a systematic review

OBJECTIVE: To assess the evidence for the effectiveness of clinical practice guidelines (CPGs) in improving patient outcomes in primary care. DATA SOURCES: A search of the MEDLINE, HEALTHPLAN, CINAHL and FAMLI databases was conducted to identify studies published between Jan. 1, 1980, and Dec. 31, 1995, concerning the use of guidelines in primary medical care. The keywords used in the search were "clinical guidelines," "primary care," "clinical care," "intervention," "randomized controlled trial" and "effectiveness." STUDY SELECTION: Studies of the use of CPGs were selected if they involved a randomized experimental or quasi-experimental method, concerned primary care, were related to clinical care and examined patient outcomes. Of 91 trials of CPGs identified through the search, 13 met the criteria for inclusion in the critical appraisal. DATA EXTRACTION: The following data were extracted, when possible, from the 13 trials: country and setting, number of physicians, number of patients (and the proportion followed to completion), length of follow-up, study method (including random assignment method), type of intervention, medical condition treated and effect on patient outcomes (including clinical and statistical significance, with confidence intervals). DATA SYNTHESIS: The most common conditions studied were hypertension (7 studies), asthma (2 studies) and cigarette smoking (2 studies). Four of the studies followed nationally developed guidelines, and 9 used locally developed guidelines. Six studies involved computerized or automated reminder systems, whereas the others relied on small-group workshops and education sessions. Only 5 of the 13 trials (38%) produced statistically significant results. CONCLUSION: There is very little evidence that the use of CPGs improves patient outcomes in primary medical care, but most studies published to date have used older guidelines and methods, which may have been insensitive to small changes in outcomes. Research is needed to determine whether the newer, evidence-based CPGs have an effect on patient outcomes.     

Meta-analysis of benzodiazepine use in the treatment of insomnia

OBJECTIVE: To systematically review the benefits and risks associated with the use of benzodiazepines to treat insomnia in adults. DATA SOURCES: MEDLINE and the Cochrane Controlled Trials Registry were searched for English-language articles published from 1966 to December 1998 that described randomized controlled trials of benzodiazepines for the treatment of insomnia. Key words included "benzodiazepines" (exploded), "randomized controlled trial" and "insomnia." Bibliographies of relevant articles were reviewed for additional studies and manufacturers of benzodiazepines were asked to submit additional randomized controlled trial reports not in the literature. STUDY SELECTION: Articles were considered for the meta-analysis if they were randomized controlled trials involving patients with insomnia and compared a benzodiazepine with placebo or another active agent. Of the 89 trials originally identified, 45 met our criteria, representing a total of 2672 patients. DATA EXTRACTION: Data were extracted regarding the participants, the setting, details of the intervention, the outcomes (including adverse effects) and the methodologic quality of the studies. DATA SYNTHESIS: The meta-analyses of sleep records indicated that, when compared with placebo, benzodiazepines decreased sleep latency by 4.2 minutes (non-significant; 95% confidence interval (CI -0.7 to 9.2) and significantly increased total sleep duration by 61.8 minutes (95% CI 37.4 to 86.2). Patient-reported outcomes were more optimistic for sleep latency; those randomized to benzodiazepine treatment estimated a sleep latency decrease of 14.3 minutes (95% CI 10.6 to 18.0). Although more patients receiving benzodiazepine treatment reported adverse effects, especially daytime drowsiness and dizziness or light-headedness (common odds ratio 1.8, 95% CI 1.4 to 2.4), dropout rates for the benzodiazepine and placebo groups were similar. Cognitive function decline including memory impairment was reported in several of the studies. Zopiclone was not found to be superior to benzodiazepines on any of the outcome measures examined. INTERPRETATION: The use of benzodiazepines in the treatment of insomnia is associated with an increase in sleep duration, but this is countered by a number of adverse effects. Additional studies evaluating the efficacy of nonpharmacological interventions would be valuable.     

Meta-analysis of benzodiazepine use in the treatment of acute alcohol withdrawal

OBJECTIVE: To analyse the evidence for the efficacy and potential harmful effects of benzodiazepines compared with other therapies in the treatment of acute alcohol withdrawal. DATA SOURCES: MEDLINE and the Cochrane Controlled Trials Registry were searched for English-language articles published from 1966 to December 1997 that described randomized controlled trials (RCTs) of benzodiazepines in the treatment of acute alcohol withdrawal. Key words included "benzodiazepines" (exploded) and "randomized controlled trial." Bibliographies of relevant articles were reviewed for additional RCTs, and manufacturers of benzodiazepines were asked to submit additional RCT reports not in the literature. STUDY SELECTION: Articles were considered for the meta-analysis if they were RCTs involving patients experiencing acute alcohol withdrawal and comparing a benzodiazepine available in Canada with placebo or an active control drug. Of the original 23 trials identified, 11 met these criteria, representing a total of 1286 patients. DATA EXTRACTION: Data were extracted regarding the participants, the setting, details of the intervention, the outcomes (including adverse effects) and the methodologic quality of the studies. DATA SYNTHESIS: The meta-analysis of benefit (therapeutic success within 2 days) showed that benzodiazepines were superior to placebo (common odds ratio [OR] 3.28, 95% confidence interval [CI] 1.30-8.28). Data on comparisons between benzodiazepines and other drugs, including beta-blockers, carbamazepine and clonidine, could not be pooled, but none of the alternative drugs was found to be clearly more beneficial than the benzodiazepines. The meta-analysis of harm revealed no significant difference between benzodiazepines and alternative drugs in terms of adverse events (common OR 0.67, 95% CI 0.34-1.32) or dropout rates (common OR 0.68, 95% CI 0.47-0.97). INTERPRETATION: Benzodiazepines should remain the drugs of choice for the treatment of acute alcohol withdrawal.     

No magic bullets: a systematic review of 102 trials of interventions to improve professional practice.

OBJECTIVE: To determine the effectiveness of different types of interventions in improving health professional performance and health outcomes. DATA SOURCES: MEDLINE, SCISEARCH, CINAHL and the Research and Development Resource Base in CME were searched for trials of educational interventions in the health care professions published between 1970 and 1993 inclusive. STUDY SELECTION: Studies were selected if they provided objective measurements of health professional performance or health outcomes and employed random or quasi-random allocation methods in their study designs to assign individual subjects or groups. Interventions included such activities as conferences, outreach visits, the use of local opinion leaders, audit and feedback, and reminder systems. DATA EXTRACTION: Details extracted from the studies included the study design; the unit of allocation (e.g., patient, provider, practice, hospital); the characteristics of the targeted health care professionals, educational interventions and patients (when appropriate); and the main outcome measure. DATA SYNTHESIS: The inclusion criteria were met by 102 trials. Areas of behaviour change included general patient management, preventive services, prescribing practices, treatment of specific conditions such as hypertension or diabetes, and diagnostic service or hospital utilization. Dissemination-only strategies, such as conferences or the mailing of unsolicited materials, demonstrated little or no changes in health professional behaviour or health outcome when used alone. More complex interventions, such as the use of outreach visits or local opinion leaders, ranged from ineffective to highly effective but were most often moderately effective (resulting in reductions of 20% to 50% in the incidence of inappropriate performance). CONCLUSION: There are no "magic bullets" for improving the quality of health care, but there are a wide range of interventions available that, if used appropriately, could lead to important improvements in professional practice and patient outcomes.     

Prognosis of delirium in elderly hospital patients.

OBJECTIVE: To determine the prognosis of delirium in elderly patients. DATA SOURCES: MEDLINE was searched for relevant articles published from January 1980 to March 1992. The bibliographies of identified articles were searched for additional references. STUDY SELECTION: Eight reports (involving 573 patients with delirium) met the following inclusion criteria: original research, published in English or French, prospective study design, diagnosis based on acute deterioration in mental state, sample of at least 20 patients, patients aged 60 years or over and follow-up of at least 1 week. The validity of the studies was independently assessed according to the criteria for prognostic studies established by McMaster University, Hamilton, Ont. No study met all the criteria. DATA EXTRACTION: Information about the patient sample, length of follow-up and results was systematically abstracted from each report and tabulated. DATA SYNTHESIS: A meta-analysis of the outcomes indicated that elderly patients with delirium had a mean length of stay of 20.7 days. One month after admission 46.5% were in institutions, and 14.2% had died; only 54.9% had improved mentally. Six months after admission 43.2% were in institutions. Compared with unmatched control subjects they had longer hospital stays, higher mortality rates at 1 month and higher rates of institutional care at 1 and 6 months. The presence of severe physical illness or dementia may have been related to some outcomes. CONCLUSIONS: Delirium in the elderly appears to have a poor prognosis. However, this finding may have been confounded by the presence of concomitant dementia or severe physical illness. Future studies must pay attention to methods and design, particularly the composition of study populations and the control of extraneous prognostic factors.     

Skepticism, statistical methods, and the cigarette: a historical analysis of a methodological debate

The discipline of modern "risk factor" epidemiology was in its formative stages in the early 1950s, when epidemiologic studies revealed a strong association between cigarette smoking and lung cancer mortality. Many medical scientists and physicians were reluctant to accept these studies as a demonstration of causation because the methods were "statistical" and involved data collected in uncontrolled conditions outside the laboratory. But a substantial number of senior biostatisticians and epidemiologists also voiced concerns, albeit more methodologically sophisticated, about the quality of the evidence at the time. Statistical methods were just beginning to work their way into medicine and public health, and many epidemiologists and statisticians were concerned about the potential misuse of these methods by untrained investigators. When studies of smoking and lung cancer gained increasing publicity and were being used to recommend public health policies, some prominent epidemiologists and statisticians highlighted this debate in their efforts to pursue methodological reform. Participants in the debate over smoking and lung cancer saw the need for explicit and rigorous standards for evaluating etiologic hypotheses, but they held conflicting views about what those standards should be. These diverging views reflect an underlying tension within the discipline of epidemiology between the search for "objective" methods of scientific inference and the practical needs of public health research that persists today.     

Unemployment and mortality among Finnish men, 1981-5.

OBJECTIVE--To ascertain whether, after controlling for several relevant background variables simultaneously, unemployment is related to mortality and to assess whether this relation is causal or whether unhealthy people are more likely to become unemployed. DESIGN--Prospective study of mortality in Finland during 1981-5 based on 1980 census data on 30-54 year old wage earner men and with particular attention to unemployment in the year before the census. SETTING--Research project at the University of Helsinki. SUBJECTS--All wage earner men in Finland aged 30-54 at the 1980 census. MAIN OUTCOME MEASURES--Causes of death during 1981-5 and duration of unemployment in the year before the census. Background variables controlled for were age, socioeconomic state, marital state, and health. The data were analysed by log linear regression models. RESULTS--During the study period 1981-5, which covered almost 2.7 million person years, there were 9810 deaths. After controlling for all background variables relative total mortality among unemployed versus employed men was 1.93 (95% confidence interval 1.82 to 2.05). The excess mortality was highest in accidental and violent causes of death (relative mortality 2.51; 95% confidence interval 2.28 to 2.76). For circulatory diseases the relative death rate was 1.54 (95% confidence interval 1.40 to 1.70), but among neoplasms only lung cancer was associated with excess mortality. Selection for unemployment based on age, socioeconomic state, and marital state was evident but no such selection was detected based on health. Effects of unemployment on mortality were more pronounced with increasing duration of unemployment. CONCLUSIONS--The relative excess mortality of unemployed men in Finland cannot fully be explained by demographic, social, and health variables preceding unemployment. Unemployment therefore seems to have an independent causal effect on male mortality. Further studies are needed to elucidate the mechanisms between unemployment and mortality.     

Helicobacter pylori infection as a cause of gastritis,duodenal ulcer,gastric cancer and nonulcer dyspepsia: a systematic overview.

OBJECTIVE: To evaluate current evidence for a causal relation between Helicobacter pylori infection and gastritis, duodenal ulcer, gastric cancer and nonulcer dyspepsia. DATA SOURCES: A MEDLINE search for articles published in English between January 1983 and December 1992 with the use of MeSH terms Helicobacter pylori, gastritis, duodenal ulcer, gastric cancer, dyspepsia and clinical trial; abstracts were excluded. Six journals and Current Contents were searched manually for pertinent articles published in that time frame. STUDY SELECTION: Original studies with at least 25 patients, case reports and reviews that examined the relation between H. pylori and the four gastrointestinal disorders; 350 articles were on gastritis, 122 on duodenal ulcer, 44 on gastric cancer and 96 on nonulcer dyspepsia. DATA EXTRACTION: The quality of the studies was rated independently on a four-point scale. The strength of the evidence was assessed using a six-point scale for each of the eight established guidelines for determining a causal relation. DATA SYNTHESIS: There was conclusive evidence of a causal relation between H. pylori infection and histologic gastritis. Koch''s postulates for the identification of a microorganism as the causative agent of a disease were fulfilled for H. pylori as a causative agent of gastritis. There was strong evidence that H. pylori is the main cause of duodenal ulcers not induced by nonsteroidal anti-inflammatory drugs, but all of Koch''s postulates were not fulfilled. There was moderate epidemiologic evidence of an association between chronic H. pylori infection and gastric cancer. There was a lack of convincing evidence of a causal association between H. pylori and nonulcer dyspepsia. CONCLUSIONS: The evidence supports a strong causal relation between H. pylori infection and gastritis and duodenal ulcer and a moderate relation between such infection and gastric cancer. Further studies are needed to clarify the role of H. pylori in these disorders. Thus far, there is no evidence of a causal relation between H. pylori and nonulcer dyspepsia.     

Depression in elderly medical inpatients: a meta-analysis of outcomes

OBJECTIVE: To determine the prognosis of elderly medical inpatients with depression. DATA SOURCES: A MEDLINE search for relevant articles published from January 1980 to September 1996 and a search of the PSYCH INFO database for articles published from January 1984 to September 1996. The bibliographies of identified articles were searched for additional references. STUDY SELECTION: Eight reports (involving 265 patients with depression) met the following 5 inclusion criteria: original research, published in English or French, population of general medical inpatients, mean age of depressed patients 60 years and over, and affective state reported as an outcome. The validity of the studies was assessed according to the criteria for prognostic studies described by the Evidence-Based Medicine Working Group. DATA EXTRACTION: Information about the patient population, the proportion of cases detected and treated by attending physicians, the length of follow-up, the affective outcome and the prognostic factors was abstracted from each report. DATA SYNTHESIS: All of the studies had some methodologic limitations. A meta-analysis of outcomes at 3 months or less indicated that 18% of patients were well, 43% were depressed and 22% were dead. At 12 months or more, 19% were well, 29% were depressed and 53% were dead. Factors associated with worse outcomes included more severe depression, more serious physical illness and symptoms of depression before admission. CONCLUSIONS: Elderly medical inpatients who are depressed appear to have a very poor prognosis: the recovery rate among these patients is low and the mortality rate high.     

The Mental Health Consequences of the Recession: Economic Hardship and Employment of People with Mental Health Problems in 27 European Countries

Objectives

A period of economic recession may be particularly difficult for people with mental health problems as they may be at higher risk of losing their jobs, and more competitive labour markets can also make it more difficult to find a new job. This study assesses unemployment rates among individuals with mental health problems before and during the current economic recession.

Methods

Using individual and aggregate level data collected from 27 EU countries in the Eurobarometer surveys of 2006 and 2010, we examined changes in unemployment rates over this period among individuals with and without mental health problems.

Results

Following the onset of the recession, the gap in unemployment rates between individuals with and without mental health problems significantly widened (odds ratio: 1.12, 95% confidence interval: 1.03, 1.34). This disparity became even greater for males, and individuals with low levels of education. Individuals with mental health problems living in countries with higher levels of stigmatizing attitudes regarding dangerousness of people with mental illness were more vulnerable to unemployment in 2010, but not 2006. Greater agreement that people with mental health problems have themselves to blame, was associated with lower likelihood of unemployment for individuals with and without mental health problems.

Conclusion

These findings study suggest that times of economic hardship may intensify social exclusion of people with mental health problems, especially males and individuals with lower education. Interventions to combat economic exclusion and to promote social participation of individuals with mental health problems are even more important during times of economic crisis, and these efforts should target support to the most vulnerable groups.     

The health of Indians in Canadian cities: a challenge to the health care system

It is well known that Canadian native people living on reserves have high morbidity and mortality rates, but less is known about the health of those who migrated to urban centres. Several studies have shown that these people have high rates of mental health problems, specific diseases, injuries, infant death and hospital admission. In addition, there is evidence that cultural differences create barriers to their use of health care facilities. The low socioeconomic status, cultural differences and discrimination that they find in cities are identified as the primary blocks to good health and adequate health care. More epidemiologic studies need to be done to identify health problems, needs and barriers to health care. Federal, provincial and civic governments along with the appropriate departments of faculties of medicine should begin working with native organizations to improve the health of native people living in Canada''s cities.     

Relationship of Self-Rated Health with Fatal and Non-Fatal Outcomes in Cardiovascular Disease: A Systematic Review and Meta-Analysis

Background

People who rate their health as poor experience higher all-cause mortality. Study of disease-specific association with self-rated health might increase understanding of why this association exists.

Objectives

To estimate the strength of association between self-rated health and fatal and non-fatal cardiovascular disease.

Methods

A comprehensive search of PubMed MEDLINE, EMBASE, CINAHL, BIOSIS, PsycINFO, DARE, Cochrane Library, and Web of Science was undertaken during June 2013. Two reviewers independently searched databases and selected studies. Inclusion criteria were prospective cohort studies or cohort analyses of randomised trials with baseline measurement of self-rated health with fatal or non-fatal cardiovascular outcomes. 20 studies were pooled quantitatively in different meta-analyses. Study quality was assessed using Newcastle-Ottawa scales.

Results

‘Poor’ relative to ‘excellent’ self-rated health (defined by most extreme categories in each study, most often’ poor’ or ‘very poor’ and ‘excellent’ or ‘good’) was associated over a follow-up of 2.3–23 years with cardiovascular mortality in studies: where varying degrees of adjustments had been made for cardiovascular disease risk (HR 1.79 (95% CI 1.50 to 2.14); 15 studies, I2 = 71.24%), and in studies reporting outcomes in people with pre-existing cardiovascular disease or ischaemic heart disease symptoms (HR 2.42 (95% CI 1.32 to 4.44); 3 studies; I2 = 71.83%). ‘Poor’ relative to ‘excellent’ self rated health was also associated with the combined outcome of fatal and non-fatal cardiovascular events (HR 1.90 (95% CI 1.26 to 2.87); 5 studies; I² = 68.61%), Self-rated health was not significantly associated with non-fatal cardiovascular disease outcomes (HR 1.66 (95% CI 0.96 to 2.87); 5 studies; I2 = 83.60%).

Conclusions

Poor self rated health is associated with cardiovascular mortality in populations with and without prior cardiovascular disease. Those with current poor self-rated health may warrant additional input from health services to identify and address reasons for their low subjective health.     

Translating guidelines into practice: a systematic review of theoretic concepts,practical experience and research evidence in the adoption of clinical practice guidelines

OBJECTIVE: To recommend effective strategies for implementing clinical practice guidelines (CPGs). DATA SOURCES: The Research and Development Resource Base in Continuing Medical Education, maintained by the University of Toronto, was searched, as was MEDLINE from January 1990 to June 1996, inclusive, with the use of the MeSH heading "practice guidelines" and relevant text words. STUDY SELECTION: Studies of CPG implementation strategies and reviews of such studies were selected. Randomized controlled trials and trials that objectively measured physicians'' performance or health care outcomes were emphasized. DATA EXTRACTION: Articles were reviewed to determine the effect of various factors on the adoption of guidelines. DATA SYNTHESIS: The articles showed that CPG dissemination or implementation processes have mixed results. Variables that affect the adoption of guidelines include qualities of the guidelines, characteristics of the health care professional, characteristics of the practice setting, incentives, regulation and patient factors. Specific strategies fell into 2 categories: primary strategies involving mailing or publication of the actual guidelines and secondary interventional strategies to reinforce the guidelines. The interventions were shown to be weak (didactic, traditional continuing medical education and mailings), moderately effective (audit and feedback, especially concurrent, targeted to specific providers and delivered by peers or opinion leaders) and relatively strong (reminder systems, academic detailing and multiple interventions). CONCLUSIONS: The evidence shows serious deficiencies in the adoption of CPGs in practice. Future implementation strategies must overcome this failure through an understanding of the forces and variables influencing practice and through the use of methods that are practice- and community-based rather than didactic.     

The Effect of Financial Compensation on Health Outcomes following Musculoskeletal Injury: Systematic Review

The effect of financial compensation on health outcomes following musculoskeletal injury requires further exploration because results to date are varied and controversial. This systematic review identifies compensation related factors associated with poorer health outcomes following musculoskeletal injury. Searches were conducted using electronic medical journal databases (Medline, CINAHL, Embase, Informit, Web of Science) for prospective studies published up to October 2012. Selection criteria included: prognostic factors associated with validated health outcomes; six or more months follow up; and multivariate statistical analysis. Studies solely measuring return to work outcomes were excluded. Twenty nine articles were synthesised and then assessed using GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology to determine evidence levels. The results were mixed. There was strong evidence of an association between compensation status and poorer psychological function; and legal representation and poorer physical function. There was moderate evidence of an association between compensation status and poorer physical function; and legal representation and poorer psychological function. There was limited evidence of an association between compensation status and increased pain. In seven studies the association depended on the outcome measured. No studies reported an association between compensation related factors and improved health outcomes. Further research is needed to find plausible reasons why compensation related factors are associated with poorer health following musculoskeletal injury.     

Regional Inequalities in Lung Cancer Mortality in Belgium at the Beginning of the 21st Century: The Contribution of Individual and Area-Level Socioeconomic Status and Industrial Exposure

Being a highly industrialized country with one of the highest male lung cancer mortality rates in Europe, Belgium is an interesting study area for lung cancer research. This study investigates geographical patterns in lung cancer mortality in Belgium. More specifically it probes into the contribution of individual as well as area-level characteristics to (sub-district patterns in) lung cancer mortality. Data from the 2001 census linked to register data from 2001–2011 are used, selecting all Belgian inhabitants aged 65+ at time of the census. Individual characteristics include education, housing status and home ownership. Urbanicity, unemployment rate, the percentage employed in mining and the percentage employed in other high-risk industries are included as sub-district characteristics. Regional variation in lung cancer mortality at sub-district level is estimated using directly age-standardized mortality rates. The association between lung cancer mortality and individual and area characteristics, and their impact on the variation of sub-district level is estimated using multilevel Poisson models. Significant sub-district variations in lung cancer mortality are observed. Individual characteristics explain a small share of this variation, while a large share is explained by sub-district characteristics. Individuals with a low socioeconomic status experience a higher lung cancer mortality risk. Among women, an association with lung cancer mortality is found for the sub-district characteristics urbanicity and unemployment rate, while for men lung cancer mortality was associated with the percentage employed in mining. Not just individual characteristics, but also area characteristics are thus important determinants of (regional differences in) lung cancer mortality.     

Air Pollution and Respiratory Mortality in Los Angeles

An epidemiologic study in Los Angeles showed a regular statistical association between respiratory mortality and the spatial distributions of ozone and particulate matter. There was an irregular association of respiratory mortality with maximum temperature. These findings are consistent with those of other studies relating respiratory morbidity to oxidant and particulate air pollution, and suggest that these pollutants may be health hazards.