Surface fluorescence resonance energy transfer studies on interfacial adsorption of Thermomyces (humicola) lanuginosa lipase, using monomolecular films of cis-parinaric acid.

The fluorescence resonance energy transfer (FRET) technique was adapted to study the process whereby lipase is adsorbed to monomolecular lipid films spread at the air-water interface. When cis-parinaric acid (cis-PnA) was spread over an aqueous subphase before the injection of sodium taurodeoxycholate (NaTDC) and Thermomyces lanuginosa lipase (TLL), no FRET was observed. Under these conditions, no adsorption of TLL was detected using an ELISA. In contrast, FRET occurred when cis-PnA was spread over an aqueous subphase containing NaTDC and TLL. The FRET signals observed were attributed to the interactions between the adsorbed TLL and the cis-PnA monomolecular films. Comparisons between the fluorescence emission spectra corresponding to the bulk phase and the aspirated film, in the presence and absence of TLL, showed that cis-PnA was undetectable in the bulk phase. We concluded that the FRET originated from the interface and not from the bulk phase. Using surface FRET, we estimated that the surface excess of the catalytically inactive mutant, TLL(S146A), was 1.6 higher than that present in the wild-type TLL. This finding is in agreement with independent measurements of the surface excess of TLL and TLL(S146A) on monomolecular films of cis-PnA.

Process of care and outcomes for elderly patients hospitalized with peptic ulcer disease: results from a quality improvement project.

CONTEXT: Since publication in 1994 of guidelines for management of peptic ulcer disease (PUD), trends in physician practice and outcomes related to guideline application have not been evaluated. OBJECTIVES: To describe changes in process of care that occurred in a quality improvement program for patients hospitalized with PUD and to evaluate associations between in-hospital treatment of PUD and 1-year rehospitalization for PUD and mortality in a subset of these patients. DESIGN, SETTING, AND PATIENTS: Cohort study of 4292 sequential Medicare beneficiaries hospitalized at acute care hospitals with a principal diagnosis of PUD in 5 states (Colorado, Georgia, Connecticut, Oklahoma, and Virginia) in 1995 (baseline) and 1997 (remeasurement); outcomes were evaluated for 752 patients in Colorado. MAIN OUTCOME MEASURES: Changes in rates of screening for Helicobacter pylori infection, treatment for H pylori infection, screening for nonsteroidal anti-inflammatory drug (NSAID) use, counseling about NSAID use; outcomes included rehospitalization for PUD and all-cause mortality within 1 year of discharge in Colorado. RESULTS: Screening for H pylori infection increased significantly (12%-19% increase; P<.001) in each of the 5 states. Treatment of H pylori infection increased in each state and was significantly increased for the entire group of hospitalizations examined (8% increase overall; P =.001). Despite increased screening, detection of H pylori infection was less frequent than expected in every state, (13%-24%) and did not increase in any state. Screening for and counseling about NSAIDs did not significantly increase overall or in any state. In the Colorado cohort, the proportion of patients rehospitalized was unchanged in 1995 (8.9%) and 1997 (6.8%), and 124 patients (16%) in the combined 1995 and 1997 cohorts died within 1 year. Treatment for H pylori was not associated with a reduction in rehospitalization within 1 year (adjusted odds ratio [OR], 1.24; 95% confidence interval [CI], 0.65-2.36) or with a reduction in mortality (adjusted OR, 1.08; 95% CI, 0.68-1.71). Counseling about NSAID use was associated with a decrease in risk of 1-year rehospitalization for PUD (adjusted OR, 0.47; 95% CI, 0.22-0.99) and risk of all-cause mortality (adjusted OR, 0.44; 95% CI, 0.26-0.75). CONCLUSIONS: This quality improvement program for elderly patients with PUD resulted in increased screening for H pylori and increased treatment of H pylori infection but no change in counseling about NSAID use. However, with the low prevalence of H pylori detected, treatment of H pylori infection was not associated with a reduction in repeat hospitalization for PUD or subsequent mortality, whereas counseling about the risks of using NSAIDs was associated with a reduction in the risk of both outcomes.

Motor vehicle crash fatalities: A comparison of Hispanic and non-Hispanic motorists in Colorado.

STUDY OBJECTIVES: We compare the population-based death rates from traffic crashes in the Hispanic and non-Hispanic white populations in a single state, and compare fatally injured Hispanic and non-Hispanic drivers with respect to safety belt use, alcohol involvement, speeding, vehicle age, valid licensure, and urban-rural location. METHODS: Hispanic and non-Hispanic white motorists killed in traffic crashes in 1991-1995 were studied (n=2,272). Data from death certificates (age, sex, education, race, and ethnicity) and the Fatality Analysis Reporting System (FARS; driver, vehicle, and crash information) were merged. Average annual age-adjusted fatality rates were calculated; to compare Hispanic and non-Hispanic white motorists, rate ratios (RR) and 95% confidence intervals (CIs) were calculated. Odds ratios (ORs), adjusted for age, sex, and rural locale, were calculated to measure the association between Hispanic ethnicity and driver and crash characteristics. RESULTS: Eighty-five percent of FARS records were matched to death certificates. Compared with non-Hispanic white motorists, Hispanics had higher crash-related fatality rates overall (RR 1.75, 95% CI 1.60 to 1.92) and for drivers only (RR 1.62, 95% CI 1.41 to 1.85). After adjustment for age, sex, and rural locale, Hispanic drivers had higher rates of safety belt nonuse (OR 1.81, 95% CI 1.20 to 2.72), legal alcohol intoxication (OR 2.73, 95% CI 1.97 to 3.79), speeding (OR 1.36, 95% CI 0.99 to 1.88), and invalid licensure (OR 2.58, 95% CI 1.78 to 3.75). The average vehicle age for Hispanic drivers (10.1 years, 95% CI 9.3 to 11.0) was greater than for non-Hispanic white motorists (8.8 years, 95% CI 8.4 to 9.2). CONCLUSION: Compared with non-Hispanic whites, Hispanic drivers have higher rates of safety belt nonuse, speeding, invalid licensure and alcohol involvement, with correspondingly higher rates of death in traffic crashes. As traffic safety emerges as a public health priority in Hispanic communities, these data may help in developing appropriate and culturally sensitive interventions.

Modeling of gas dynamics for a laser-generated plasma: propagation into low-pressure gases

The physical phenomena involved during three-dimensional axisymmetric laser-induced plasma expansion into background gas are numerically studied. For this purpose, a multispecies hydrodynamic model is developed which considers the effects of mass and ambipolar diffusions, thermal conduction, viscosity, and nonequilibrium conditions for ionization. This model is applied to describe quantitatively the Si plasma plume expansion into Ar or He gases. It is shown that the mechanism of plasma expansion depends critically on both the pressure and mass of the background gas. The shock front expansion is found to be strongly correlated with ion dynamics. A pronounced difference between heavy-particle and electron temperatures indicates a persistent lack of equilibrium between the heavy particle and the electron in the plasma plume expansion. The Si atoms of the rarefied plume are essentially driven by the backward-moving background gas as a result of a mass diffusion process. It is also noted that the diffusion processes are only important in the last expansion stage, and are less significant in the first stage. Therefore, it is shown that a computation which does not include diffusion effects (Euler equations) can adequately describe only the earliest stage of plasma expansion into background gas. The ability of the Navier-Stokes hydrodynamic multispecies model to predict the key role of the background gas type (Ar, He) and pressure is demonstrated.

Adolescent suicide and household access to firearms in Colorado: results of a case-control study.

PURPOSE: To determine whether, compared with age- and sex-matched controls who did not commit suicide, adolescents who committed suicide by firearms were more likely to have had household access to firearms (after adjusting for significant risk factors for adolescent suicide). METHODS: A case-control study design was used; case subjects were Colorado adolescents who committed suicide between 1991 and 1993; controls were sex- and age-matched adolescents who were randomly selected from the same school the subjects had attended. Interviews were conducted with the parent or guardian of cases and controls. RESULTS: Of the 36 case subjects in this study, 67% committed suicide using a gun obtained from their home. Adolescent suicide victims who committed suicide by firearms were significantly more likely to have a firearm in their home (72%) than age- and sex-matched community controls (50%), after adjusting for significant risk factors. Conduct disorder and previous mental health treatment were also found to be independent risk factors for adolescent firearm suicide. CONCLUSIONS: Two types of public health interventions to prevent adolescent firearm suicides are likely to be successful: (a) limiting household access to firearms, and (b) identifying adolescents at high risk of firearm suicide.

Comparison of health status, socioeconomic characteristics, and knowledge and use of HIV-related resources between HIV-infected women and men.

OBJECTIVES: The authors compared socioeconomic characteristics, and knowledge and use of human immunodeficiency virus (HIV)-related resources and health status measures between HIV-infected women and men registered within the Denver Health and Hospitals health care system. METHODS: Data collected through two Centers for Disease Control-funded surveillance initiatives (Adult Spectrum of Disease and Supplement to HIV/AIDS Surveillance) were linked. Health status measures were obtained using the Medical Outcomes Study (MOS-20) questionnaire. To compare health status measures between genders, men were matched to women based on disease stage, intravenous drug use, race, years of education, employment status, and age. RESULTS: Among all patients interviewed (n = 419), women (n = 52) were more likely to be minority, uneducated, intravenous drug users, and at earlier stages of HIV-disease than men (n = 367). Employment status was not significantly different. Knowledge of available services was generally good among both genders. Women received public assistance and had health insurance (Medicaid) more often than men. Women used support services, social work, and shelter assistance less often than men. The matched pairs analysis (n = 46 pairs) showed no significant differences between genders in physical and social function, mental health, pain, or general health perceptions; however, role function was better in women than in men (P<0.02). CONCLUSIONS: When controlling for factors that may influence health and access to health care, HIV disease generally impacts the health status of both genders similarly. Women scored higher in role function which may reflect family caretakers' responsibilities. Although knowledge of HIV-related resources was similar by gender, men made contact more often suggesting areas for enhanced outreach toward women.

Tobacco use and other risk behaviors among adolescents in an STD clinic.

BACKGROUND: This study examined the potential for tobacco use and other health risk behavior interventions in the context of an urban sexually transmitted diseases (STD) clinic. METHODS: A cross-sectional survey of two populations. Adolescents seen at an STD clinic or at the teen clinic of a community health center completed a self-administered computer survey in 1996. Risk behaviors, attitudes, and readiness to stop smoking were analyzed for 225 patients at the STD clinic and 248 patients at the teen clinic. RESULTS: Compared with adolescents in the teen clinic, adolescents in the STD clinic were more likely to have smoked frequently (OR 1.7, 95% CI 1.1, 3.0), used any illegal drug (OR 2.7, 95% CI 1.3, 5.5), recently binged on alcohol (OR 1.7, 95% CI 1.0, 2.8), and had more than 10 lifetime sexual partners (OR 1.9, 95% CI 1.0, 3.4). Weapon carrying, readiness to stop smoking, and attitudes toward smoking did not differ between sites. CONCLUSIONS: Cigarette smoking and other health risk behaviors are more prevalent among adolescents in an STD clinic than among adolescents in a community health center. STD clinics are potential sites for cigarette, alcohol, and drug use interventions among "hard to reach" adolescents.

Urban and rural traumatic brain injuries in Colorado.

PURPOSE: The purpose of this study was to compare and contrast the epidemiology of traumatic brain injury among urban and rural residents of Colorado. METHODS: Cases of traumatic brain injury (ICD 800, 801, 803, 804, 850-854) for 1991 and 1992 from the Colorado surveillance system of hospitalized and fatal traumatic brain injuries were used. Urban cases resided in counties designated by the U.S. Census Bureau as metropolitan statistical areas (MSA). Rural cases were divided into two groups: "rural, nonremote," if the country of residence was adjacent to an MSA county or if it had a population of 2500, and "rural, remote," if not. RESULTS: Average annual age-adjusted rates of hospitalized and fatal traumatic brain injury varied significantly from 97.8 per 100,000 population for the most urban group to 172.1 per 100,000 population for the residents of rural, remote counties. Similarly, total mortality ranged from 18.1 per 100,000 population among residents of the most urban counties to 33.8 among residents of rural, remote counties. Prehospital mortality ranged from 10.0 to 27.7 traumatic brain injuries per 100,000 population. CONCLUSIONS: These results provide justification for expanding efforts to prevent traumatic brain injury to include the small, but high-risk group of residents in rural areas.

Tracking community sentinel events: breast cancer mortality and neighborhood risk for advanced-stage tumors in Denver.

OBJECTIVES: The incidence of related sentinel events--breast cancer mortality and neighborhood-specific morbidity for advanced stage at diagnosis--were calculated for women likely to use a community health center in Denver, Colo. METHODS: For the center's service area, neighborhoods (n = 37) were defined by program use. Mortality rates and proportional hazards regression models were estimated for 4189 breast cancer cases recorded between 1979 and 1990. Neighborhood-specific standard morbidity ratios of advanced-stage tumors were based on age-specific rates applied to the entire community. RESULTS: Service area residents were more likely to present with advanced tumors (odds ratio [OR] = 1.4; 95% [CI] = 1.2, 1.5). After adjustment, advanced-stage disease and socioeconomic-demographic status, but not race-ethnicity, contributed significantly to survival. Two neighborhoods (6.5% of the population at risk) with standard morbidity ratios of 2.1 (95% CI = 1.3, 3.4) and 1.7 (95% CI = 1.2, 2.5) accounted for 42% of the excess cases of advanced-stage tumors between 1986 and 1990. CONCLUSIONS: Neighborhood variation in advanced-stage cancer can serve as the basis for efforts to improve access to breast cancer screening.

Usefulness of human immunodeficiency virus post-test counseling by telephone for low-risk clients of an urban sexually transmitted diseases clinic.

BACKGROUND: Failure of clients to return for post-test counseling for human immunodeficiency virus (HIV) has been noted consistently as a problem with HIV counseling and testing in sexually transmitted disease clinics. GOALS: To assess trends in the rates of HIV post-test counseling in an urban sexually transmitted disease clinic. To determine the usefulness of providing post-test counseling by telephone to clients at low risk for HIV as a means of increasing post-test counseling rates and efficiency of clinic operations. STUDY DESIGN AND METHODS: Human immunodeficiency virus post-test counseling rates were evaluated among clients of a sexually transmitted disease clinic from January 1990 through May 1994. Low-risk clients (n = 1,304) from July 1994 through September 1994 were given the option of obtaining negative HIV test results by telephone. Rates of post-test counseling within 45 days were compared with historical controls from March 1994 through May 1994, during which time a return visit was required. RESULTS: The rate of post-test counseling increased significantly from 1990 to 1992 but remained stable thereafter. After the introduction of post-test counseling by telephone, 704 of 1,304 low-risk clients (54.0%) obtained post-test counseling compared with 476 of 1,187 (40.1%) clients during the control period (odds ratio = 1.75; 95% confidence interval = 1.50-2.06). Post-test counseling rates increased especially among clients younger than 20 years of age (30.6% versus 52.7%) and among those with multiple new sex partners in the last month (31.6% versus 56.1%). CONCLUSIONS: Telephone post-test counseling is an effective method of increasing access for low-risk clients attending sexually transmitted diseases clinics and may be especially useful for those who are otherwise unlikely to obtain post-test counseling.

Chlamydia trachomatis antibody titers and hysterosalpingography in predicting tubal disease in infertility patients.

OBJECTIVE: To determine if the number of diagnostic laparoscopies done on women without tubal adhesive disease could be reduced by testing for tubal disease with Chlamydia trachomatis antibody titers and hysterosalpingography (HSG), either singly or together. DESIGN: Historical prospective chart review. SETTING: The Colorado Kaiser Permanente Reproductive Endocrinology Clinic. PATIENTS: All 703 infertility patients who had C. trachomatis antibody titers done from March 2, 1988 to April 30, 1992. The final study group was comprised of 218 patients who had antibody titers, HSG, and laparoscopy. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Sensitivity, negative predictive value, and false-positive rate were the test characteristics of interest. Tubal disease was identified by laparoscopy. RESULTS: For HSG testing, the sensitivity was 78% and the negative predictive value was 85%. For C. trachomatis titers, the sensitivity was also 78% and the negative predictive value was 82%. Ninety-five percent confidence intervals for sensitivity and negative predictive value overlapped, indicating that there was no significant difference. However, false-negative rates were the same for the two tests, but false-positive rates were lowest for HSG and series testing. CONCLUSIONS: To minimize false-positive tests and thus, to minimize unnecessary laparoscopies, HSG testing either alone or combined with the C. trachomatis antibody titer as series tests yielded a significantly lower false-positive rate. In our study group, if both tests were negative, tubal disease was identified on laparoscopy in only 5% of cases. Choice of most cost-effective test sequence will depend on who bears the cost. Further studies of cost-benefit using well-defined testing sequences are needed to determine if C. trachomatis antibody titers in series with HSG would be more cost effective than HSG alone in detecting tubal disease.

Risk factors for delayed immunization against measles, mumps, and rubella in Colorado two-year-olds.

OBJECTIVES: 1) To examine a wide range of potential risk factors for delayed childhood immunization against measles, mumps, and rubella and 2) to determine the parental response to proposed solutions regarding the problem of delayed childhood immunization. DESIGN: A case-control study in which subjects had (controls) or had not (cases) received measles, mumps, and rubella vaccine (MMR) by 2 years of age. Parents of subjects were also surveyed to find out whether they thought selected proposals to improve immunization rates would be successful. RESULTS: Maternal education of high school or less at the time of the child's birth, more than or equal to two moves between birth and age 2, maternal age < 21 years of age at the time of the child's birth, more than or equal to two older siblings, participation in The Special Supplemental Food Program for Women, Infants, and Children (WIC), participation in the federal food stamp program, and incorrect knowledge of the recommended age for MMR significantly elevated the odds ratio (OR) for delayed immunization. At least two older siblings (OR = 3.2), maternal age < 21 years of age at the time of the child's birth (OR = 2.8), and incorrect knowledge of the recommended age for MMR (OR = 2.7) remained significant risk factors in a multivariate logistic regression model. Insurance status and cost factors were not significant risk factors for delayed immunization. Parents though that reminders for immunization and a central record system would have made obtaining immunizations easier. CONCLUSIONS: Based on our findings of the importance of immunization knowledge and demographic characteristics as risk factors for delayed immunization, we suggest that a message (the recommended age for immunizations) and a target group for that message (families who move frequently, have older children, and are headed by younger parents) be evaluated as an intervention to improve immunization rates.

Children with special health-care needs in Texas.

A comprehensive system for the delivery of care to children with special healthcare needs and to their families has been developed by the department of pediatrics of The University of Texas Health Science Center at San Antonio. A description of the structure and operations of this system is presented and offered as a model for the state of Texas.

Mandatory seatbelts: epidemiologic, financial, and medical rationale from the Colorado matched pairs study.

In what approximated a controlled clinical trial for efficacy of seatbelts, the Colorado matched pairs study examined 256 crashes meeting the following criteria: driver plus front-seat passenger, one belted (SB) and one nonbelted (NSB) occupant, and at least one occupant injured. Nearly half (119 of 256) of the SB partners escaped injury, while only 16% (41 of 256) of the NSB group were as fortunate. To ascertain a differential effect the 160 pairs discordant for injury were analyzed. The relative odds for injury in the SB group was 0.34 (95% Cl: 0.24, 0.49) of that in the NSB group. Likewise, relative odds for any medical costs in the SB group was reduced to 0.24 (95% Cl: 0.14, 0.43) and for hospitalization to 0.29 (95% Cl: 0.10, 0.80). Sixty-five percent of the SB group had no medical costs in contrast to only 29% of the NSB group. Altogether the NSB group accounted for 76% of the medical costs and 72% of the hospitalizations. This study establishes the effectiveness of seatbelts in reducing nonfatal injuries using epidemiologic, financial, and medical data.

Evaluation of an intervention to change benzodiazepine-prescribing behavior in a prepaid group practice setting.

To determine the effect of two levels of educational intervention on benzodiazepine-prescribing behavior in an elderly population in a controlled prepaid group practice (PPGP) setting, we designed a prospective controlled trial, with six-month follow-up. Our setting was a 270,000 member group-model PPGP in Colorado, from 1990 to 1991. Participants included 91 physicians, 62 men and 29 women; median age was 38.7 years. Group 1 received a one-on-one educational presentation by a clinical pharmacist, written educational materials, a brief follow-up visit, and feedback with recommendations. Group 2 received only a face-to-face presentation, given to departmental groups, as well as the same written educational materials used in group 1. Controls received no intervention. Our primary outcome measure was the benzodiazepine "on/off" status of the elderly PPGP members. The secondary outcome measure was the median change (preintervention minus postintervention) in a standardized amount of benzodiazepines prescribed per physician. Logistic regression analysis failed to show a significant effect on postintervention benzodiazepine on/off status between study groups, when controlling for preintervention on/off status, PPGP-member age, PPGP-member gender, and all possible interactions. Analysis of variance failed to demonstrate an effect of either intervention on the median change in standardized amount of benzodiazepines prescribed per physician, with groups 1, 2, and controls yielding values of -278 (range: -4,137, 2,844), -330 (-1,531, 1,358), and -541 (range: -3,716, 2,185), respectively. We conclude that strategies effective in changing physician prescribing behavior in other settings may not be effective in a PPGP setting with benzodiazepines in the elderly as the target for change.

Detection of injury-prone behaviors among internal medicine patients.

OBJECTIVES: 1) To describe the prevalence of eight injury-prone behaviors (IPBs) and the associations of these behaviors with ten standard chronic disease and sociodemographic risk factors (CDSRFs) among internal medicine patients and 2) to identify a subset of patients with multiple IPBs who might be at particularly high risk of injury. DESIGN: Cross-sectional survey. SETTING: The University of Colorado Health Sciences Center general internal medicine clinic. PATIENTS: Four hundred ninety-two consecutive continuity care patients were eligible. The response rate was 94.3% (464/492). INSTRUMENT: A validated, self-administered questionnaire. MAIN RESULTS: Thirty-four percent of patients did not wear safety belts regularly and 32% had no smoke detector in their homes. Nearly 26% of patients had firearms at home and 6% had a loaded and unlocked gun at home. Fourteen percent of patients had seriously thought about suicide and 6% had attempted suicide. In the prior month, 10% had ridden with a drunk driver, and 4% had driven after drinking too much. Of patients aged 65 years or older, 50% had had recent falls. After adjustment for other CDSRFs, problem drinking was the CDSRF most frequently associated with IPBs. Among men, problem drinking was significantly associated with drinking and driving (OR = 35.3), safety belt non-use (OR = 4.3), and previous thoughts of or attempts at suicide (OR = 6.2). Among women, problem drinking was significantly associated with drinking and driving (OR = 8.7). Among men, being unmarried was the demographic risk factor associated with the most IPBs. Of all IPBs, safety belt non-use was most frequently associated with CDSRFs (ORs ranged from 2.8 to 4.4). Men with three or more IPBs were more likely to be problem drinkers (OR = 9.6), smokers (OR = 15.8), obese (OR = 6.3), and unmarried (OR = 67.1). CONCLUSIONS: 1) Injury-prone behaviors are common among patients attending a university-based internal medicine clinic; 2) men and women have substantially different patterns of risk factor associations; 3) CDSRFs, such as problem drinking smoking, and being unmarried, are associated with many IPBs; 4) safety belt non-use is the IPB associated with the most CDSRFs; and 5) CDSRFs appear to cluster in men with multiple IPBs, suggesting that screening for high-risk individuals may be feasible in clinical practice.

Work-related aviation fatalities in Colorado 1982-1987.

On-the-job deaths related to aviation are the seventh leading cause of fatal occupational injury in the United States. In Colorado, they comprise 37% of all air transport deaths. A review of all occupational aviation-related fatalities in Colorado during 1982-1987 identified 86 deaths. Data sources were death certificates, Workers' Compensation records, and National Transportation Safety Board reports. Of the fatalities, 5 involved commercial air service, 16 were military personnel, and 65 (76%) were associated with general aviation. Non-military occupations included 21 pilots, 5 flight instructors, 4 crop sprayers, and 3 search and rescue workers or firefighters. There were 18 people going to or from work sites. The 15 weather cases, 7 aircraft malfunctions, and 4 power transmission wire strikes were the most significant factors in two-thirds of the crashes of civilian aircraft. Even experienced pilots exercised poor judgement. The prominence of general aviation in work-related aviation fatalities indicates a need for greater attention to the safety of workers whose jobs entail flying.

Clinically important respiratory effects of dust exposure and smoking in British coal miners.

A unique data set of 3,380 British coal miners has been reanalyzed with major focus on nonpneumoconiotic respiratory conditions. The aim was to assess the independent contribution of smoking and exposure to respirable dust to clinically significant measures of respiratory dysfunction. Exposure to coal-mine dust was monitored over a 10-yr period. Medical surveys provided estimates of prior dust exposure and recorded respiratory symptoms. Each man's FEV1 was compared with the level predicted for his age and height by an internally derived prediction equation for FEV1. Four respiratory indices were considered at the end of the 10-yr period: FEV1 less than 80%, chronic bronchitis, chronic bronchitis with FEV1 less than 80%, and FEV1 less than 65%. Results were uniformly incorporated into logistic regression equations for each condition. The equations include coefficients for age, dust, and when indicated, an interaction term for age and dust. Dust-related increases in prevalence of each of the 4 conditions were statistically significant and were similar for smokers and nonsmokers at the mean age (47 yr). There was no evidence that smoking potentiates the effect of exposure to dust. Estimates of prevalences at the mean age of all 4 measures of respiratory dysfunction were greater in smokers. At intermediate and high dust exposure the prevalence of the 4 conditions in nonsmokers approached the prevalence in smokers at hypothetically zero dust exposure. Both smoking and dust exposure can cause clinically important respiratory dysfunction and their separate contributions to obstructive airway disease in coal miners appear to be additive.(ABSTRACT TRUNCATED AT 250 WORDS)