Publications

A survey-based COPD severity scoring algorithm could prove useful for targeted disease management and risk-adjustment. For this purpose, we sought to prospectively validate a COPD severity score that had previously been cross-sectionally validated. Using a population-based sample of 267 adults with self-reported physician-diagnosed COPD, we examined the extent to which this COPD severity score predicts future respiratory hospitalizations, emergency department (ED) visits, and outpatient visits. Structured telephone interviews, conducted at baseline and on an annual basis in two subsequent years, determined COPD severity scores and health-care utilization. A basic predictive model for respiratory-specific health-care utilization was developed using sociodemographics, tobacco history, and medical comorbidity data in multivariate logistic regression analysis. The added predictive value of the COPD severity score over and above this basic model was then evaluated by testing the change in model concordance indices. Our analysis demonstrated that the COPD severity score did, in fact, increase the concordance-index of models predicting future respiratory hospitalizations (increase from 80% to 87%; P = 0.03), ED visits (64% to 82%, P = 0.003), and outpatient visits (59% to 77%, P < 0.0001). In a separate analysis, both a greater baseline severity score and worsening of the severity score over time were prospectively associated with each outcome studied (P < 0.05 for each). In conclusion, the COPD severity score adds predictive value in estimating future respiratory-specific health-care utilization and is longitudinally responsive to evolving changes in COPD status over time. This severity score may be used to adjust for disease severity or to identify high-risk populations.

BACKGROUND

Area-level socioeconomic status (SES) may play an important role in drug abuse patterns, including related health outcomes. This may be particularly relevant for gamma-hydroxybutyrate (GHB), which is prototypical of "party" drug abuse.

METHODS

We retrospectively reviewed GHB-related cases reported to the California Poison Control System (CPCS; January 1, 1999 through June 30, 2007). We limited analysis to CPCS calls containing a residential zip code (ZC). The CPCS data were extracted for key case characteristics, including the residential ZC. We linked cases to corresponding 2000 U.S. Census data for area-level measures of SES and demographics. We used multiple logistic regression analysis to test the associations between area-level SES and GHB case severity, taking into account area-level demographics and individual-level GHB high-risk behaviors.

RESULTS

We analyzed 210 cases. Taking into account area-level demographics (age and racial mix; urbanicity) and GHB-related high-risk behaviors (use of GHB congeners; GHB-dependence; co-ingestion of other agents), we associated higher area-level SES with greater GHB case severity. There was 40% increased likelihood of major GHB adverse health outcomes for every $100,000 incremental increase in median home values (OR 1.41; 95% CI 1.1-1.8). For median annual household income (per $10,000), the association was similar (OR 1.39; 95% CI 1.0-1.9).

CONCLUSION

Higher area-level SES is associated with greater GHB-related case severity. This study may serve as a model using a geographic information system (GIS) approach to study the population-based correlates of drugs of abuse reported through poison control surveillance.

BACKGROUND

Exposure to traffic has been associated with asthma outcomes in children, but its effect on asthma in adults has not been well studied.

OBJECTIVE

To test the hypothesis that lung function and health status are associated with traffic exposures.

METHODS

We measured FEV(1) % predicted, general health status using the Physical Component Scale of the 12-item Short Form (SF-12 PCS), and quality of life (QoL) using the Marks Asthma Quality of Life questionnaire in a cohort of adults with asthma or rhinitis (n = 176; 145 with asthma). We assessed exposures to traffic by geocoding subjects' residential addresses and assigning distance to roadways. Associations between distance to nearest roadway and distance to nearest major roadway and FEV(1) % predicted or SF-12 PCS were studied by using linear regression.

RESULTS

FEV(1) % predicted was positively associated with distance from both nearest roadway (P = .01) and nearest major roadway (P = .02). SF-12 PCS and QoL were not significantly associated with either traffic variable. Adjustment for income, smoking, and obesity did not substantively change the associations of the traffic variables with FEV(1) % predicted (P = .04 for nearest roadway and P = .02 for nearest major roadway) and did not cause associations with either SF-12 PCS or QoL to become significant.

CONCLUSIONS

Traffic exposure was associated with decreased lung function in adults with asthma.

BACKGROUND

Previous cross-sectional studies have shown that job change due to breathing problems at the workplace (respiratory work disability) is common among adults of working age. That research indicated that occupational exposure to gases, dust and fumes was associated with job change due to breathing problems, although causal inferences have been tempered by the cross-sectional nature of previously available data. There is a need for general population-based prospective studies to assess the incidence of respiratory work disability and to delineate better the roles of potential predictors of respiratory work disability.

METHODS

A prospective general population cohort study was performed in 25 centres in 11 European countries and one centre in the USA. A longitudinal analysis was undertaken of the European Community Respiratory Health Survey including all participants employed at any point since the baseline survey, 6659 subjects randomly sampled and 779 subjects comprising all subjects reporting physician-diagnosed asthma. The main outcome measure was new-onset respiratory work disability, defined as a reported job change during follow-up attributed to breathing problems. Exposure to dusts (biological or mineral), gases or fumes during follow-up was recorded using a job-exposure matrix. Cox proportional hazard regression modelling was used to analyse such exposure as a predictor of time until job change due to breathing problems.

RESULTS

The incidence rate of respiratory work disability was 1.2/1000 person-years of observation in the random sample (95% CI 1.0 to 1.5) and 5.7/1000 person-years in the asthma cohort (95% CI 4.1 to 7.8). In the random population sample, as well as in the asthma cohort, high occupational exposure to biological dust, mineral dust or gases or fumes predicted increased risk of respiratory work disability. In the random sample, sex was not associated with increased risk of work disability while, in the asthma cohort, female sex was associated with an increased disability risk (hazard ratio 2.8, 95% CI 1.3 to 5.9).

CONCLUSIONS

Respiratory work disability is common overall. It is associated with workplace exposures that could be controlled through preventive measures.

BACKGROUND

The aim of this paper is to highlight emerging data on occupational attributable risk in asthma. Despite well documented outbreaks of disease and the recognition of numerous specific causal agents, occupational exposures previously had been relegated a fairly minor role relative to other causes of adult onset asthma. In recent years there has been a growing recognition of the potential importance of asthma induced by work-related exposures

METHODS

We searched Pub Med from June 1999 through December 2007. We identified six longitudinal general population-based studies; three case-control studies and eight cross-sectional analyses from seven general population-based samples. For an integrated analysis we added ten estimates prior to 1999 included in a previous review.

RESULTS

The longitudinal studies indicate that 16.3% of all adult-onset asthma is caused by occupational exposures. In an overall synthesis of all included studies the overall median PAR value was 17.6%.

CONCLUSION

Clinicians should consider the occupational history when evaluating patients in working age who have asthma. At a societal level, these findings underscore the need for further preventive action to reduce the occupational exposures to asthma-causing agents.

Secondhand smoke (SHS) is a major contributor to indoor air pollution. Because it contains respiratory irritants, it may adversely influence the clinical course of persons with chronic obstructive pulmonary disease (COPD). We used data from nonsmoking members of the FLOW cohort of COPD (n = 809) to elucidate the impact of SHS exposure on health status and exacerbations (requiring emergency department visits or hospitalization). SHS exposure was measured by a validated survey instrument (hours of exposure during the past week). Physical health status was measured by the SF-12 Physical Component Summary Score and disease-specific health-related quality of life (HRQL) by the Airways Questionnaire 20-R. Health care utilization for COPD was determined from Kaiser Permanente Northern California computerized databases. Compared to no SHS exposure, higher level SHS exposure was associated with poorer physical health status (mean score decrement -1.78 points; 95% confidence interval [CI] -3.48 to -0.074 points) after controlling for potential confounders. Higher level SHS exposure was also related to poorer disease-specific HRQL (mean score increment 0.63; 95% CI 0.016 to 1.25) and less distance walked during the Six-Minute Walk test (mean decrement -50 feet; 95% CI -102 to 1.9). Both lower level and higher level SHS exposure was related to increased risk of emergency department (ED) visits (hazard ratio [HR] 1.40; 95% CI 0.96 to 2.05 and HR 1.41; 95% CI 0.94 to 2.13). Lower level and higher level SHS exposure were associated with a greater risk of hospital-based care for COPD, which was a composite endpoint of either ED visits or hospitalizations for COPD (HR 1.52; 95% CI 1.06 to 2.18 and HR 1.40; 95% CI 0.94 to 2.10, respectively). In conclusion, SHS was associated with poorer health status and a greater risk of COPD exacerbation. COPD patients may comprise a vulnerable population for the health effects of SHS.

STUDY OBJECTIVE

To examine obstructive sleep apnea (OSA) as a risk factor for work disability.

PATIENTS AND SETTING

Consecutive patients referred to the University of California San Francisco Sleep Disorders Center with suspected OSA (n = 183).

DESIGN

All patients underwent overnight polysomnography after completing a written survey which assessed work disability due to sleep problems, occupational characteristics and excessive daytime sleepiness (EDS) defined as an Epworth Sleepiness Scale score > 10.

RESULTS

Among 150 currently employed patients, 83 had OSA on polysomnography (apnea-hypopnea index > or = 5). Compared with patients in whom both OSA and EDS were absent, patients with the combination of OSA and EDS were at higher risk of both recent work disability (adjusted odds ratio [OR], 13.7; 95% confidence interval [CI], 3.9-48) and longer-term work duty modification (OR, 3.6; CI, 1.1-12). When either OSA or EDS were absent, the strength of the association with work disability was less than when both OSA and EDS were present. When OSA was examined without respect to EDS, patients with OSA were at increased risk of recent work disability relative to patients without OSA (OR 2.6; 95% CI 1.2-5.8), but the association of OSA with longer-term work duty modification did not meet standard criteria for statistical significance (OR = 2.0, 95% CI 0.8-5.0).

CONCLUSIONS

The combination of OSA and EDS contributes to work disability, and OSA by itself contributes to recent work disability. These findings should highlight to employers and clinicians the importance of OSA in the workplace to encourage patients to be screened for OSA, particularly in situations of decreased productivity associated with EDS.

OBJECTIVE

To examine occupational risk for Chronic Obstructive Pulmonary Disease (COPD).

METHODS

We randomly recruited 233 subjects aged 55 to 75 reporting a physician's diagnosis of COPD, emphysema, or chronic bronchitis. Interviews assessed cigarette smoking and longest held job, identifying exposure to vapors, gas, dust, or fumes (VGDF). Lung function was assessed in n = 138. Comparison data were derived from a sample of referents without COPD.

RESULTS

VGDF was reported in 123 (53%) of 233 cases versus 577 (34%) of 1709 referents. VGDF was associated with COPD (Odds Ratio [OR] 2.5; 95% CI = 1.9 to 3.4); the population attributable fraction was 32%. In the lung function subset, the FEV1/FVC was <70% in 79 (57%); 35 (44%) reported VGDF associated with an OR = 1.6 (95% CI = 0.99 to 2.6) and population attributable fraction 17%.

CONCLUSIONS

These data support an important role for occupational exposures in COPD.

INTRODUCTION

Secondhand smoke (SHS) contains respiratory irritants and has the potential to adversely affect adults with chronic obstructive pulmonary disease (COPD), but few studies have evaluated the impact of SHS on COPD.

METHODS

We used data from 72 nonsmoking participants in a cohort study of COPD. Urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was measured as an indicator of longer term SHS exposure, whereas urine cotinine was assessed as a measure of more recent exposure. The impact of SHS exposure on COPD-related health status was examined using multivariate linear regression (controlling for age, sex, race, educational attainment, and smoking history). Health status was measured using a validated COPD severity score, reported dyspnea, a standard health status measure (Short Form-12), and activity restriction.

RESULTS

The urine NNAL-to-creatinine ratio (per interquartile increment) was associated with greater COPD severity (mean score increase 1.7 points; 95% CI 0.6-2.8; p = .0003). Higher urine NNAL was also related to greater dyspnea, poorer physical health status, and more restricted activity (p < or = .05 in all cases). When considered simultaneously, longer term exposure (NNAL) had a greater negative impact on COPD status than shorter term exposure (cotinine).

DISCUSSION

Urine NNAL can be used to estimate longer term SHS exposure and negatively affects a number of health outcomes among adults with COPD. Screening for and prevention of SHS exposure among persons with COPD may be beneficial.

BACKGROUND

Prior research on the risk of depression in chronic obstructive pulmonary disease (COPD) has yielded conflicting results. Furthermore, we have an incomplete understanding of how much depression versus respiratory factors contributes to poor health-related quality of life.

METHODS

Among 1202 adults with COPD and 302 demographically matched referents without COPD, depressive symptoms were assessed using the 15-item Geriatric Depression Score. We measured COPD severity using a multifaceted approach, including spirometry, dyspnea, and exercise capacity. We used the Airway Questionnaire 20 and the Physical Component Summary Score to assess respiratory-specific and overall physical quality of life, respectively.

RESULTS

In multivariate analysis adjusting for potential confounders including sociodemographics and all examined comorbidities, COPD subjects were at higher risk for depressive symptoms (Geriatric Depression Score >or=6) than referents (odds ratio [OR] 3.6; 95% confidence interval [CI], 2.1-6.1; P <.001). Stratifying COPD subjects by degree of obstruction on spirometry, all subgroups were at increased risk of depressive symptoms relative to referents (P <.001 for all). In multivariate analysis controlling for COPD severity as well as sociodemographics and comorbidities, depressive symptoms were strongly associated with worse respiratory-specific quality of life (OR 3.6; 95% CI, 2.7-4.8; P <.001) and worse overall physical quality of life (OR 2.4; 95% CI, 1.8-3.2; P <.001).

CONCLUSIONS

Patients with COPD are at significantly higher risk of having depressive symptoms than referents. Such symptoms are strongly associated with worse respiratory-specific and overall physical health-related quality of life, even after taking COPD severity into account.