The health impact of undiagnosed airflow obstruction in a national sample of United States adults.

UNLABELLED: To determine the health and functional impact of undiagnosed airflow obstruction for subjects in the general population, we used data obtained as part of the Third National Health and Nutrition Examination Survey (NHANES III). Categories of diagnosed and undiagnosed airflow obstruction were defined using questionnaire responses and spirometric results. Health and functional impact of airflow obstruction was assessed from responses to questions about general health status, walking 1/4 mile, lifting or carrying something as heavy as 10 lb, or needing help with personal care. Undiagnosed airflow obstruction (12.0%) was more common than doctor-diagnosed chronic obstructive pulmonary disease (COPD) (3.1%) or asthma (2.7%). Although undiagnosed airflow obstruction was usually very mild, approximately 5% of the entire sample had an FEV(1) less than 75% predicted. After adjusting for smoking, obesity, and comorbid conditions, the risk of impaired health and functional status with undiagnosed airflow obstruction was independently associated with severity of FEV(1) impairment. For males and females, ever smoking was strongly associated with all types of airflow obstruction, diagnosed or not. However, among females with airflow obstruction, 12.2% to 35.2% never smoked. Undiagnosed airflow obstruction is common in the general population of the United States and is associated with impaired health and functional status. KEYWORDS: airflow obstruction; spirometry; health impact; screening

Developing a community-specific health-related quality of life (HRQOL) questionnaire for asthma: the Asthma-Specific Quality of Life Questionnaire for Native American Adults (AQLQ-NAA).

The Asthma Quality of Life Questionnaire for Native American Adults (AQLQ-NAA) was developed by modifying the Asthma Quality of Life Questionnaire-Marks (AQLQ-M) using the focus group technique. The 19-item AQLQ-NAA has emphasis on restrictions in social, community, and cultural activities. Higher scores indicate a better quality of life. The modified questionnaire was administered to a sample of 51 Native American adults with asthma at the Albuquerque USPHS Indian Hospital and its affiliated field clinics. Principal components analysis identified three domains with eigenvalues greater than 1.00: Community and Social Restrictions (CSR), Psychological Impact (PIM), and Symptoms (SYM). Cronbach's coefficient alpha for the AQLQ-NAA was 0.95 and ranged from 0.82 to 0.93 for the individual domains, indicating good internal consistency. The AQLQ-NAA score correlated negatively and significantly to urgent care visits, physician visits, and total number of medications taken for asthma in the past 6 and 12 months (p < 0.05). Additionally, the AQLQ-NAA score was correlated positively and significantly to medication adherence in the past 6 and 12 months (p < 0.05). Similar patterns of correlations were found with all three domain scores. These results indicated that there is evidence for the construct validity of the AQLQ-NAA and its domains. The AQLQ-NAA should provide a useful measure of HRQOL in asthma-specific medical interventions for the population in which it was developed.

Health care utilization in chronic obstructive pulmonary disease. A case-control study in a health maintenance organization.

BACKGROUND: Information about health care utilization and costs among patients with chronic obstructive pulmonary disease (COPD) is needed to improve care and for appropriate allocation of resources for patients with COPD (COPD patients or cases) in managed care organizations. METHODS: Analysis of all inpatient, outpatient, and pharmacy utilization of 1522 COPD patients continuously enrolled during 1997 in a 172,484-member health maintenance organization. Each COPD case was matched with 3 controls (n = 4566) by age (+/-5 years) and sex. Information on tobacco use and comorbidities was obtained by chart review of 200 patients from each group. RESULTS: Patients with COPD were 2.3 times more likely to be admitted to the hospital at least once during the year, and those admitted had longer average lengths of stay (4.7 vs 3.9 days; P<.001). Mean costs per case and control were $5093 vs $2026 for inpatient services, $5042 vs $3050 for outpatient services, and $1545 vs $739 for outpatient pharmacy services, respectively (P<.001 for all differences). Patients with COPD had a longer smoking history (49.5 vs 34.9 pack-years; P =.002) and a higher prevalence of smoking-related comorbid conditions and were more likely to use cigarettes during the study period (46.0% vs 13.5%; P<.001). CONCLUSIONS: Health care utilization among COPD patients is approximately twice that of age- and sex-matched controls, with much of the difference attributable to smoking-related diseases. In this health maintenance organization, inpatient costs were similar to and outpatient costs were much higher than national averages for COPD patients covered by Medicare.

Occupational and environmental risk factors for idiopathic pulmonary fibrosis: a multicenter case-control study. Collaborating Centers.

Occupational exposures were investigated in a multicenter case-control study of clinically and histologically diagnosed idiopathic pulmonary fibrosis (IPF), a chronic diffuse interstitial lung disease of unknown etiology. Results are based on 248 cases, aged 20-75 years, diagnosed at 16 referral centers between January 1989 and July 1993. There were 491 controls ascertained by random digit dialing and matched to cases on sex, age, and geographic region. Data were collected using a standard telephone questionnaire. Occupational factors were based on a detailed history of jobs lasting 6 months or more and job activity, hobby, and specific substance checklists. Several occupational factors, adjusted for age and smoking in conditional multivariate logistic regression analyses, were significantly associated with IPF: farming (odds ratio (OR) = 1.6, 95% confidence interval (CI): 1.0, 2.5); livestock (OR = 2.7, 95% CI: 1.3, 5.5); hairdressing (OR = 4.4, 95% CI: 1.2, 16.3); metal dust (OR = 2.0, 95% CI: 1.0, 4.0); raising birds (OR = 4.7, 95% CI: 1.6, 14.1); stone cutting/polishing (OR = 3.9, 95% CI: 1.2, 12.7); and vegetable dust/animal dust (OR = 4.7, 95% CI: 2.1, 10.4). Interaction was detected between smoking and exposure to livestock (p = 0.06) and farming (p = 0.08). Results confirm previous studies showing increased risk associated with dusty environments.

Utilization in COPD: patient characteristics and diagnostic evaluation.

STUDY OBJECTIVES: Information on current practices of COPD diagnosis and treatment is needed to identify opportunities for improving care. This study describes the clinical characteristics and diagnostic evaluations of COPD patients in a health maintenance organization (HMO) and a university-affiliated county medical center (UMC). DESIGN: Cross-sectional survey performed in a 174,484-member regional HMO and in The University of New Mexico Hospitals and Clinics (UNMH). PATIENTS: Two hundred COPD patients from each system randomly selected from administrative databases based on discharge diagnoses. RESULTS: COPD patients in the UMC, compared to those in the HMO, were younger (mean age, 59.3 vs 66.9 years, respectively), were more likely to be using home oxygen (33% vs 20%, respectively), and had fewer chronic medical conditions (mean number of conditions, 3.1 vs 3.7, respectively) (p < 0.01 for all differences). Approximately half of the COPD patients in both groups continued to smoke cigarettes during the study year. Only 38% of patients in the HMO and 42% in the UNMH system had spirometry results documented in their medical records. CONCLUSIONS: The demographic and clinical characteristics of the COPD patients in these two health-care systems were very different, but smoking status and utilization of diagnostic tests were similar. The diagnosis of COPD in most patients was based only on a history of chronic respiratory symptoms and smoking; spirometry often was not used to confirm the diagnosis. An increased emphasis on smoking cessation and more effective utilization of spirometry are needed to improve the management of COPD in these health-care systems.

Idiopathic pulmonary fibrosis: survival in population based and hospital based cohorts.

BACKGROUND: To ascertain whether findings from hospital based clinical series can be extended to patients with idiopathic pulmonary fibrosis (IPF) in the general population, the survival of patients with IPF in a population based registry was compared with that of a cohort of patients with IPF treated at major referral hospitals and the factors influencing survival in the population based registry were identified. METHODS: The survival of 209 patients with IPF from the New Mexico Interstitial Lung Disease Registry and a cohort of 248 patients with IPF who were participating in a multicentre case-control study was compared. The determinants of survival for the patients from the Registry were determined using life table and proportional hazard modelling methods. RESULTS: The median survival times of patients with IPF in the Registry and case-control cohorts were similar (4.2 years and 4.1 years, respectively), although the average age at diagnosis of the Registry patients was greater (71.7 years versus 60.6 years, p < 0.01). After adjusting for differences in age, sex, and ethnicity, the death rate within six months of diagnosis was found to be greater in the Registry patients (relative hazard (RH) 6.32, 95% CI 2.19 to 18.22) but more than 18 months after diagnosis the death rate was less (RH 0.35, 95% CI 0.19 to 0.66) than in the patients in the case-control study. Factors associated with poorer prognosis in the Registry included advanced age, severe radiographic abnormalities, severe reduction in forced vital capacity, and a history of corticosteroid treatment. CONCLUSIONS: The adjusted survival of patients with IPF in the general population is different from that of hospital referrals which suggests that selection biases affect the survival experience of referral hospitals.

Ethnic differences in the prevalence of nonmalignant respiratory disease among uranium miners.

OBJECTIVES: This study (1) investigates the relationship of nonmalignant respiratory disease to underground uranium mining and to cigarette smoking in Native American, Hispanic, and non-Hispanic White miners in the Southwest and (2) evaluates the criteria for compensation of ethnic minorities. METHODS: Risk for mining-related lung disease was analyzed by stratified analysis, multiple linear regression, and logistic regression with data on 1359 miners. RESULTS: Uranium mining is more strongly associated with obstructive lung disease and radiographic pnuemoconiosis in Native Americans than in Hispanics and non-Hispanic Whites. Obstructive lung disease in Hispanic and non-Hispanic White miners is mostly related to cigarette smoking. Current compensation criteria excluded 24% of Native Americans who, by ethnic-specific standards, had restrictive lung disease and 4.8% who had obstructive lung disease. Native Americans have the highest prevalence of radiographic pneumoconiosis, but are less likely to meet spirometry criteria for compensation. CONCLUSIONS: Native American miners have more nonmalignant respiratory disease from underground uranium mining, and less disease from smoking, than the other groups, but are less likely to receive compensation for mining-related disease.

Mortality rates from cryptogenic fibrosing alveolitis in seven countries.

BACKGROUND: Registered mortality from cryptogenic fibrosing alveolitis (CFA) in England and Wales has increased substantially since the specific International Classification of Diseases code for CFA was introduced in 1979. However, since a significant proportion of deaths from CFA are misclassified as post inflammatory fibrosis (PIF), it is possible that the observed rise in CFA mortality is due to diagnostic transfer from this code. To investigate this, and to assess mortality trends in other countries, annual CFA and PIF mortality data from England and Wales, USA, Australia, Scotland, Canada, New Zealand, and Germany were analysed. METHODS: Crude annual mortality rates were calculated and rates standardised by Poisson regression to allow assessment of changes over time and comparison between countries, sexes, and age groups. The relative trends in mortality from CFA and PIF were assessed by calculating the annual ratio of CFA to PIF deaths. RESULTS: Men were more likely than women to die from both CFA and PIF in all countries. The highest standardised CFA mortality rate occurred in England and Wales, and the lowest in Germany. Since 1979 mortality from CFA has increased in England and Wales, Australia, Scotland and Canada, but there was no trend in CFA mortality in New Zealand or Germany. In the USA mortality from CFA was low and has fallen. Mortality from PIF increased in all countries except New Zealand and Germany, and the highest PIF mortality, together with the greatest increase over time, was seen in the USA. Changes over time in the annual ratio of CFA to PIF deaths in all countries were small, implying that diagnostic transfer is not a major cause of the increasing CFA mortality. CONCLUSIONS: Mortality from CFA continues to increase in England and Wales and in many other countries. Diagnostic transfer from PIF does not appear to be a major cause of this.

Accuracy of mortality data for interstitial lung diseases in New Mexico, USA.

BACKGROUND: The sensitivity and accuracy of death certificates and mortality data as sources of population based data on the occurrence of interstitial lung diseases has received limited attention. To determine the usefulness of these data sources, death certificates and mortality data from patients in New Mexico were examined. METHODS: Patients with an interstitial lung disease were identified from a population based registry. For subjects who had died, diagnostic information from their death certificates and from mortality data was compared with the clinical diagnoses made before death. RESULTS: Of 385 patients with a clinical diagnosis of an interstitial lung disease, 134 died between October 1988 and August 1994. Death certificates were obtained for 96% of these patients. An interstitial lung disease was listed somewhere on the death certificate for only 46% of the patients, and as an immediate cause of death for only 15%. For the patients with an interstitial lung disease listed somewhere on the death certificate the overall concordance between the diagnoses before death and those on the death certificate was 76%. Mortality data for the State of New Mexico showed a diagnosis of interstitial lung disease to be the assigned cause of death for only 22% of the patients. The overall agreement between the diagnoses made before death and those of the state mortality data was only 21%. CONCLUSIONS: These results suggest that death certificates and state mortality data are neither sensitive nor accurate for describing the occurrence of interstitial lung diseases. This finding may partly explain the apparently low mortality rates from idiopathic pulmonary fibrosis in the USA compared with other countries.

Air pollution.

Despite progress in improving ambient air quality and reducing personal exposures to air pollutants in indoor settings, population exposures to air pollutants remain widespread and are an important public health concern. Many air pollutants are associated with adverse health effects; the most serious include development and exacerbation of asthma, loss of lung function, impaired neurobehavioral development, and death. These outcomes are the focus of current health effects research on environmental tobacco smoke and radon in indoor settings, and lead, ozone, and particulate matter outdoors. Advances in methods to measure exposures to specific pollutants and the identification of markers of individual susceptibility are providing improved data on the relation of exposure and disease, and, in turn, will improve efforts to protect public health.

The epidemiology of interstitial lung diseases.

Little epidemiologic data are available on the occurrence of interstitial lung diseases (ILDs) in the general population. To describe the prevalence and incidence of ILDs a population-based registry of patients with ILDs was established in Bernalillo County, New Mexico in October 1988. All patients 18 yr of age and older who had a clinical diagnosis of an ILD were identified during the period 10/1/88 through 9/30/90 from physician referrals, hospital discharge diagnoses, histopathology reports, and death certificates. In addition, the prevalence of preclinical or undiagnosed cases was identified by screening lung specimens from 510 autopsy cases. A total of 2,936 referrals were screened; 8.8% were prevalent cases and 6.9% were incident cases. Overall, the prevalence of ILDs was 20% higher in males (80.9 per 100,000) than in females (67.2 per 100,000). Similarly the overall incidence of ILDs was slightly more common in males (31.5 per 100,000/year) than females (26.1 per 100,000/year). The estimated prevalence of preclinical or undiagnosed ILDs among all deaths was 1.8%. The most common incident diagnosed among both sexes were pulmonary fibrosis and idiopathic pulmonary fibrosis, together accounting for 46.2% of all ILD diagnoses in males and 44.2% in females. We conclude that the occurrence of ILDs in the general population may be more common than previous estimates based on selected populations, and these disorders may frequently be unrecognized.

Silicosis and lung cancer risk in underground uranium miners.

The presence of radiographic silicosis as a risk factor for lung cancer was assessed in a case-control study conducted within a study cohort of New Mexico underground uranium miners. Chest radiographs were interpreted for the presence of silicosis for 65 lung cancer cases and 216 controls. The presence of silicosis on the chest radiograph taken closest to the start of employment or on the latest radiograph available was not associated with lung cancer risk after adjustment for cumulative exposure to radon progeny. The odds ratio associated with the presence of any type of opacity indicative of pneumoconiosis on the chest x ray closest to the start of employment was 1.33 (95% confidence interval, 0.31-5.72). For the most recent available chest x ray, the corresponding odds ratio was 1.16 (95% confidence interval, 0.35-3.84). Although the findings are limited by the relatively small number of subjects, the lack of association of silicosis with lung cancer suggests that silica exposure should not be regarded as a major uncertainty in extrapolating radon risk estimates from miners to the general population.

Acceptability of Unified Medical Language System terms as substitute for natural language general medicine clinic diagnoses.

The acceptability of using the Unified Medical Language System (UMLS) concept phrases to substitute for physicians' diagnosis statements was investigated. Physician diagnosis statements recorded in the University of New Mexico's General Medicine Clinic were input into a computer program that automatically finds the best matching UMLS concept phrases. The computer program written in C++ integrates UMLS searching and browsing with a graphical user interface. Five attending physicians in the Department of Internal Medicine rated the acceptability of the UMLS concept phrase as a substitute for the original physician statement. One hundred and ninety-five patients' notes were examined with 447 diagnosis statements recorded of which 271 statements were unique. Attending physicians rated their satisfaction with the automated UMLS substitutes on a scale of 1 (extremely dissatisfied) to 5 (extremely satisfied). Intrarater (mean 0.94) and interrater correlations (mean 0.75) were high. The mean rating was 4.0 (quite satisfied). Most (73%) of the substitution were satisfactory (rating of 4 or 5), 16% were neutral (rating of 3), and 21% were unsatisfactory (rating of 1 or 2). A review of the substitutions showed a frequent lack of clinical modifier terms in UMLS as has been previously described. Comparison to a previous study shows the broader term coverage of UMLS to be a more acceptable source of diagnosis codes than using International Classification of Diseases revision 9 alone. These results suggest that UMLS can be an effective tool for coding unconstrained physician diagnoses.

Cigarette yields of tar and nicotine and markers of exposure to tobacco smoke.

Although cigarette yields of tar and nicotine have been declining since the early 1970s, little information is available for the general population on the consequences of their use on exposure to tobacco combustion products. In a population-based sample of 298 smokers, the majority of whom were Hispanic, we examined the relationships between yields of cigarettes currently smoked and levels of salivary cotinine and end-expired carbon monoxide. Spearman correlation coefficients between the current number of cigarettes smoked and cotinine (r = 0.52) or carbon monoxide (r = 0.51) were higher than correlations between the Federal Trade Commission (FTC) nicotine data and these same markers, 0.12 and 0.05, respectively. Correlations between FTC tar and carbon monoxide yields and the biologic markers were similarly weak. In multiple linear regression models, the current number of cigarettes smoked was the most important predictor of cotinine and carbon monoxide levels (p < 0.0001). The addition of FTC tar, nicotine, or carbon monoxide to the models explained little of the variability in cotinine or carbon monoxide levels. Because FTC yields of tar and nicotine are poor predictors of exposure to tobacco combustion products, subjects' reports of cigarette brand should not be used as a primary marker of exposure in epidemiologic investigations. Furthermore, smokers need to be advised about the limitations of cigarette yield information for predicting the potential for adverse health effects of smoking.