Comparison of clinic models for patients with work-related asthma.

BACKGROUND: Work-related asthma (WRA) is a prevalent occupational lung disease that is associated with undesirable effects on psychological status, quality of life (QoL), workplace activity and socioeconomic status. Previous studies have also indicated that clinic structure may impact outcomes among patients with asthma. AIMS: To identify the impact of clinic structure on psychological status, QoL, workplace limitations and socioeconomic status of patients with WRA among two different tertiary clinic models. METHODS: We performed a cross-sectional analysis between two tertiary clinics: clinic 1 had a traditional referral base and clinical staffing while clinic 2 entirely comprised Worker's Compensation System referrals and included an occupational hygienist and a return-to-work coordinator. Beck Anxiety and Depression II Inventories (BAI and BDI-II), Marks' Asthma Quality of Life Questionnaire (M-AQLQ) and Work Limitation Questionnaire (WLQ) were used to assess outcomes for patients with WRA. RESULTS: Clinic 2 participants had a better psychological status across the four instruments compared with clinic 1 (for Beck 'Anxiety': P < 0.001 and 'Depression': P < 0.01, 'Mood' domain of M-AQLQ: NS and 'Mental Demands' domain of WLQ: P < 0.01). Clinic 2 had a greater proportion of participants with reduced income. CONCLUSIONS: Our study indicates that clinic structure may play a role in outcomes. Future research should examine this in larger sample sizes.

Work-exacerbated asthma in a workers' compensation population.

BACKGROUND: Asthma is becoming more prevalent with large numbers of individuals suffering from work-exacerbated asthma. AIMS: To examine the characteristics of workplace exposures and working days lost in relation to work-exacerbated asthma (WEA) in a workers' compensation population. METHODS: An analysis of accepted workers' compensation asthma claims in Ontario over a 5-year period. Claims among the top three industry groups were categorized based on working time lost of 1 day or less, 2-5 days and 6 days or more. Attributable agents were subdivided into dusts, smoke, chemicals and sensitizers. RESULTS: Among the asthma claims, 72% (645) fulfilled criteria for WEA from their history. The commonest industry groups were services, education and health care, with 270 claims that met our analysis requirements. Within these industry groups, education had a lower proportion of workers with short exacerbations (missing 1 day or less: 27%) while the health care industry had a higher than expected proportion of short exacerbations (55%). The agents to which WEA was attributed differed across the groups, with dusts having the highest proportion in the education group (65%), smoke in the service industry (34%) and sensitizers in health care (41%). Those agents more commonly attributed to exacerbations tended to have lower rates of prolonged exacerbation compared with less commonly involved agents. CONCLUSIONS: The morbidity of WEA and the type of agents to which it was attributed varied between industry groups.

Occupational contact allergens: are they also associated with occupational asthma?

BACKGROUND: Workplace exposures that can potentially cause both allergic occupational contact dermatitis (AOCD) and occupational asthma (OA) are not clearly identified. METHODS: Occupational contact allergens (OCAs) were identified using North American Contact Dermatitis Group (NACDG) data. Reference documents and systematic reviews were used to determine whether each OCA had been reported to potentially cause OA. The presence or absence of a sensitizer notation in occupational hygiene reference documents was also examined. RESULTS: The 10 most common OCAs were: epoxy resin*, thiuram, carba mix, nickel sulfate*, cobalt chloride*, potassium dichromate*, glyceryl thioglycolate, p-phenylenediamine*, formaldehyde* and glutaraldehyde*. Seven (indicated by *) were determined to be possible causes of OA. Information on sensitizing potential from OH reference materials contained conflicting information. CONCLUSIONS: Several common OCAs can also potentially cause OA. Inhalation and dermal exposures to these agents should be controlled and both OA and AOCD should be considered as possible health outcomes. Increased consistency in sensitizer notations is needed.

Symptoms after mould exposure including Stachybotrys chartarum, and comparison with darkroom disease.

BACKGROUND: Mould-attributed symptoms have included features which overlap with unexplained syndromes such as sick building syndrome. OBJECTIVES: We describe questionnaire and chart review findings in patients following exposure to moulds which include Stachybotrys and compare responses with two control groups. METHODS: Thirty-two patients presented with symptoms attributed to mould exposures. Exposure identification for 25 patients had reported S tachybotrys chartarum as well as other mould (Aspergillus, Penicillium), 88% at work. The remaining seven had professionally visualized or self-reported/photographic exposure evidence only. A chart review was performed and a follow-up with a questionnaire, including questions on current health status, and nonspecific symptoms. RESULTS: Cough, shortness of breath and chest tightness (at presentation) were reported in 79%, 70% and 64%, respectively, and persisted >6 weeks in 91%. Skin test(s) were positive to fungal extract(s) in 30%. Seventeen returned questionnaires were obtained 3.1 (SD 0.5) years after the initial clinic assessment. Among this subgroup, persisting asthma-like symptoms and symptoms suggestive of sick building syndrome were frequent, and similar to a group previously assessed for darkroom disease among medical radiation technologists. The mould-exposed group more commonly reported they were bothered when walking in a room with carpets, complained of a chemical or metallic taste in their mouth, and had problems in concentration when compared with a control physiotherapist group (P < 0.005). CONCLUSIONS: Although only a minority with health concerns from indoor mould exposure had demonstrable mould-allergy, a significant proportion had asthma-like symptoms. Other symptoms were also common and persistent after the initial implicated exposure.

Physician diagnosed asthma, respiratory symptoms, and associations with workplace tasks among radiographers in Ontario, Canada.

BACKGROUND: Medical radiation technologists (MRTs) or radiographers have potential exposure to chemicals including sensitisers and irritants such as glutaraldehyde, formaldehyde, sulphur dioxide, and acetic acid. AIMS: To determine the prevalence of asthma and work related respiratory symptoms among MRTs compared with physiotherapists, and to identify work related factors in the darkroom environment that are associated with these outcomes. METHODS: As part of a two component study, we undertook a questionnaire mail survey of the members of the professional associations of MRTs and physiotherapists in Ontario, Canada, to ascertain the prevalence of physician diagnosed asthma, and the prevalence in the past 12 months of three or more of the nine respiratory symptoms (previously validated by Venables et al to be sensitive and specific for the presence of self reported asthma). Information on exposure factors during the past 12 months, such as ventilation conditions, processor leaks, cleanup activities, and use of personal protective equipment was also collected. RESULTS: The survey response rate was 63.9% among MRTs and 63.1% among physiotherapists. Most analyses were confined to 1110 MRTs and 1523 physiotherapists who never smoked. The prevalence of new onset asthma (since starting in the profession) was greater among never smoking MRTs than physiotherapists (6.4% v 3.95%), and this differed across gender: it was 30% greater among females but fivefold greater among males. Compared with physiotherapists, the prevalence of reporting three or more respiratory symptoms, two or more work related, and three or more work related respiratory symptoms in the past 12 months was more frequent among MRTs, with odds ratios (ORs) (and 95% confidence intervals) adjusted for age, gender, and childhood asthma, of 1.9 (1.5 to 2.3), 3.7 (2.6 to 5.3), and 3.2 (2.0 to 5.0), respectively. Analyses examining latex glove use indicated that this was not likely to account for these differences. Among MRTs, respiratory symptoms were associated with a number of workplace and exposure factors likely to generate aerosol or chemical exposures such as processors not having local ventilation, adjusted OR 2.0 (1.4 to 3.0); leaking processor in which clean up was delayed, 2.4 (1.6 to 3.5); floor drain clogged, 2.0 (1.2 to 3.2); freeing a film jam, 2.9 (1.8 to 4.8); unblocking a blocked processor drain, 2.4 (1.6 to 3.7); and cleaning up processor chemical spill, 2.8 (1.9 to 4.2). These outcomes were not associated with routine tasks unlikely to generate exposures, such as working outside primary workplace, loading film into processor, routine cleaning of processors, or removing processed film. Males reported that they carried out a number of tasks potentially associated with irritant exposures more frequently than females, consistent with the marked increase in risk for new onset asthma. CONCLUSIONS: These findings suggest an increase of work related asthma and respiratory symptoms shown to denote asthma among MRTs, which is consistent with previous surveys. The mechanism is not known but appears to be linked with workplace factors and may involve a role for irritant exposures.

Changes in rates and severity of compensation claims for asthma due to diisocyanates: a possible effect of medical surveillance measures.

OBJECTIVES: A medical surveillance programme was introduced into Ontario for workers exposed to diisocyanates in 1983, but no mandated surveillance programme is in effect in this province for other occupational respiratory sensitisers. This study assesses changes in incidence and severity of compensated claims for occupational asthma (OA) due to diisocyanates compared with other causes, which have occurred since the introduction of this surveillance programme. METHODS: New claims for OA compensated by the Ontario Workers' Compensation Board (WCB) between 1980 and 1993 were retrospectively reviewed. Linkage was made between these data and an Ontario Ministry of Health database to assess hospital admissions for asthma from the date of onset of OA until the end of 1996. RESULTS: Numbers of claims for OA induced by diisocyanates ranged from 9-15/year in 1980-83, increased up to 55-58 claims/year in 1988-90, then fell to 19-20 claims/year by 1992-93. By contrast yearly numbers of claims for OA due to other causes increased up to 1985-87 then remained relatively stable. Duration of symptoms for OA induced by diisocyanates was shorter than for other claims and there were fewer hospital admissions among those with OA induced by diisocyanates than among those with OA induced by other causes. Occupational asthma from all causes was diagnosed earlier in claims for 1987-93 compared with 1980-86, and indicators of severity of asthma were also milder in accepted claims during 1987-93 than in earlier claims. CONCLUSIONS: Although engineering and industrial hygiene measures may have contributed to these changes, our findings are also consistent with a beneficial contribution from the medical surveillance programme for workers exposed to diisocyanates.

Outcomes of a natural rubber latex control program in an Ontario teaching hospital.

BACKGROUND: Allergy to natural rubber latex (NRL) has been frequently reported in health care workers. However, there is little published evidence of the outcome of hospital intervention programs to reduce exposure and detect cases of sensitization early. OBJECTIVE: This study assesses the effects of intervention to reduce NRL allergy in an Ontario teaching hospital with approximately 8000 employees. METHODS: A retrospective review assessed annual numbers of employees visiting the occupational health clinic, allergy clinic, or both for manifestations of NRL allergy compared with the timing of introduction of intervention strategies, such as worker education, voluntary medical surveillance, and hospital conversion to low-protein, powder-free NRL gloves. RESULTS: The number of workers identified with NRL allergy rose annually, from 1 in 1988 to 6 in 1993. When worker education and voluntary medical surveillance were introduced in 1994, a further 25 workers were identified. Nonsterile gloves were changed to low-protein, powder-free NRL gloves in 1995: Diagnoses fell to 8 workers that year, and 2 of the 3 nurses who had been off work because of asthma-anaphylaxis were able to return to work with personal avoidance of NRL products. With a change to lower protein, powder-free NRL sterile gloves in 1997, allergy diagnoses fell to 3, and only 1 new case was identified subsequently up to May 1999. No increased glove costs were incurred as a result of consolidated glove purchases. CONCLUSIONS: This program to reduce NRL allergy in employees was effectively achieved without additional glove costs while reducing expenses from time off work and workers' compensation claims.

Natural rubber latex-related occupational asthma: association with interventions and glove changes over time.

BACKGROUND: Exposure to natural rubber latex (NRL) has been recognized as a cause of occupational asthma (OA), especially among health care workers (HCWs) associated with use of gloves. Little or no population-based data are available which chart the changes over time in the number of cases of OA as this problem was increasingly recognized and then interventions instituted. METHODS: We obtained the numbers of allowed asthma claims with exposure to latex by year in the province of Ontario, Canada from the Ontario Workplace Safety and Insurance Board; details of the cases from the largest teaching hospital were reviewed. Interventions included: (1) in 1996, the Board recommended in its focus for accommodation of sensitized workers, the reduction of aerosols of latex proteins and that hospital facilities use powder-free, low-protein or nonlatex gloves; and (2) hospitals instituted latex policies and glove changes at various dates. For example, at the largest teaching hospital, interventions included education and voluntary medical surveillance in 1994; substitution of low protein, "powder-free" NRL gloves for non-sterile powdered gloves in 1995; and replacement of powdered sterile NRL gloves by lower protein, "powder-free" NRL gloves in 1997. RESULTS: Through 1999, there were 60 allowed claims for asthma in Ontario with exposure to latex; of these 49 (82%) were among HCWs. The number of claims among HCWs changed from 0 to 2 per year up to 1990; increased to 7 to 11 per year between 1991-1994; and declined to 3 per year in 1995-1996 and 1 to 2 per year in 1997-1999. Of the ten institutions having two or more OA latex claims, all claims occurred in 1996 or earlier at 8 (80%). At the largest hospital, there were five accepted claims with year of diagnosis in 1993 (1 case), 1994 (3 cases), and 1995 (1 case). CONCLUSIONS: These findings suggest that, despite the effect of increasing recognition, the introduction of gloves with reduced powder and/or protein, as well as other interventions have been associated temporally with declines in the number of cases of latex OA.

Hospitalization among workers compensated for occupational asthma.

Occupational asthma (OA) can cause persistent symptoms, but populations with OA have not been followed for the development of serious outcomes such as hospitalization. Subjects receiving compensation for OA during 1980-1993, and a comparison sample of workers with musculoskeletal injuries (INJ) were identified from the Ontario Workers' Compensation Board. We also identified for comparison a group of asthmatic patients (AP) seen at a tertiary care hospital clinic during the same period. The file was matched with the Ontario Ministry of Health data base of hospitalizations through 1996. We compared the frequency of hospitalization of the subgroups with that expected in the general population using standardized morbidity ratios (SMRs), and directly by proportional hazards regression. The study group included 844 OA claimants, 1,556 INJ claimants, and 402 AP. Although admissions for all causes combined and respiratory disease among INJ were less than expected in the general population, admissions for all causes combined exceeded that expected among OA and AP. Admissions for respiratory disease were markedly greater than expected among OA (SMR 9.2) and AP (SMR 17) because of even greater excess admissions for asthma (SMRs 45 and 81, respectively). Compared with those with INJ, those with OA were more likely to be hospitalized for all causes combined (adjusted relative risk [RR] 1.4, 95% confidence interval [CI] 1.2 to 16); cardiovascular disease (RR 1.4, 95% CI 0.9 to 2.0); respiratory disease (RR 5.4, 95% CI 3.8 to 7.7); and asthma (RR 28.1, 95% CI 10.2 to 77.2) but not for malignancies (RR 1.0) or injuries (RR 0.9). Those with OA were admitted to hospital about half as frequently as AP for respiratory disease and asthma (although this was modified by smoking status and sex), but were 30% more likely to be admitted for ischemic heart disease (IHD). Among the OA claimants, factors that were significantly associated with hospitalization for asthma included older age and exposure to agents other than isocyanates. Those with OA became less likely to be hospitalized for asthma with increasing time after onset, particularly after 5 or more years. We conclude that subjects with OA suffer higher rates of hospitalizations for all causes combined, respiratory disease, and asthma than other workers, although less than among AP seen at a tertiary care center.

Preliminary report of mortality among workers compensated for work-related asthma.

BACKGROUND: Although fatalities due to asthma have been reported among subjects with occupational asthma (OA) associated with re-exposure, groups of subjects with work-related asthma have not been systematically followed up for mortality. During a review of compensation claims for asthma in Ontario, we identified 3 respiratory deaths among subjects previously compensated for OA for whom their surviving spouses received death benefits. This suspected "cluster" prompted us to undertake an investigation to examine mortality pattern among workers compensated for work-related asthma. METHODS: Subjects receiving compensation for OA or aggravation of asthma (AA) between 1980 and 1993, and a comparison sample of workers with claims for musculoskeletal injuries during the same period were identified from the Ontario Workers' Compensation Board. We also identified another comparison group of non-compensated asthmatic patients seen at a hospital clinic during the same period. The files of those with work-related asthma were reviewed to determine if OA or AA was adequately documented. Mortality was ascertained by linkage with the Mortality Database at the Ontario Cancer Registry through 1996. We compared the mortality of the three groups with that expected in the general population of Ontario using SMRs, and directly by proportional-hazards regression. RESULTS: The study included 3,070 subjects: 1,112 with work-related OA/AA with adequate documentation, 1,556 with work-related injuries, and 402 patients with non-work-related asthma. Of the 66 deaths identified, only 2 deaths were due to asthma, both in the work-related asthma group: one from the index cluster and one not previously identified. A second index death was coded as dying from COPD not elsewhere classified (ICD9 496), while the third index death also died of asthma but there was not sufficient information documenting OA to include the subject in the analyses. As compared with the general population, there were fewer deaths than expected from most causes, except for deaths among the work-related asthma claimants and the nonwork-related asthma patients from respiratory diseases (SMRs 1.3 and 5.9, respectively; 0.5 among injury claimants), all chronic obstructive lung disease (ICD9 490-496; SMRs 2.3 and 7.7, respectively), and asthma (SMRs 18.2 and 0, respectively). In direct comparison of the work-related asthma claimants with the injury claimants, the risk of death appeared elevated from respiratory disease (RR 2.6) and ischemic heart disease (IHD) (RR 2.8) but the confidence intervals included unity. CONCLUSIONS: This preliminary report raises the possibility that serious outcomes, including excess deaths from respiratory disease, in particular asthma, may occur among those with work-related asthma even in the absence of re-exposure. However, the findings are inconclusive given that the number of deaths was small and we identified only one new asthma death in addition to the index cluster. We also observed for the first time that deaths due to circulatory disease, particularly IHD, may also be increased among such workers; this needs to be confirmed elsewhere.