Diagnosis of occupational asthma (OA) by specific inhalation challenge (SIC) can be costly and is not always available. The use of sputum testing to avoid this in some patients may be a more cost-effective alternative.
To compare the cost-effectiveness of SIC with serial measurements of sputum cell counts (sputum testing) and peak expiratory flow (PEF) monitoring.
Clinical data and testing costs for OA in 49 patients were collected during a previously published trial, modelled and compared using TreeAge Pro. Clinical outcome was the percentage of accurately diagnosed patients, using SIC as the gold standard. The PEF approach used the most accurate assessment of five experts who were blinded to SIC results. Differences in the proportion of eosinophils during periods on and off work were used for the sputum testing approach and in PEF/sputum for the combined approach. Unit costs were estimated from charges in Canadian hospitals. Data were analyzed by one-way and two-way analyses, and by probabilistic sensitivity analysis using a Monte Carlo simulation technique.
The PEF approach had an estimated accuracy of 52% and cost $365 per patient tested. Compared with PEF monitoring, sputum testing was more accurate and cost an estimated $255 for each additional OA patient correctly diagnosed. SIC costs per additional correct diagnosis were $11,032 compared with sputum testing and $6,458 compared with PEF monitoring. The combined PEF/sputum testing approach was not cost-effective in the base case analysis, but cannot be excluded according to probabilistic sensitivity analyses.
Although SIC remains the reference test to diagnose OA, when this test is not available, sputum testing is a cost-effective alternative to PEF for diagnosis of OA.
Notes
Cites: Am J Respir Crit Care Med. 1996 Aug;154(2 Pt 1):308-178756799
Recently, a genome-wide association study (GWAS) conducted in Korean subjects identified four CTNNA3 (alpha-T catenin) single nucleotide polymorphisms (SNPs) (rs10762058, rs7088181, rs1786929, and rs4378283) associated with diisocyanate-induced occupational asthma (DA). The CTNNA3 gene codes for a cadherin involved in formation of stretch-resistant cell-cell adhesions. We conducted a candidate gene association study to replicate these findings in Caucasian workers. Genotyping was performed on DNA using a 5' nuclease PCR assay collected from 410 diisocyanate-exposed and predominantly Canadian workers including 132 workers with DA confirmed by a specific inhalation challenge (DA+); 131 symptomatic workers in whom DA was excluded by a negative challenge (DA-); and 147 hexamethylene diisocyanate-exposed asymptomatic workers (AWs). As in the Korean study, highly linked CTNNA3 rs7088181 and rs10762058 SNPs (but not rs4378283 and rs1786929) were significantly associated with DA+ when compared with AWs but not in comparison with DA- workers (p = 0.05). After adjusting for potentially confounding variables of age, smoking status, and duration of exposure, minor allele homozygotes of rs7088181 and rs10762058 SNPs were at increased risk for DA compared with AWs (OR = 9.05 [95% CI: 1.69, 48.54] and OR = 6.82 [95% CI: 1.65, 28.24], respectively). In conclusion, we replicated results from the only reported GWAS study of DA demonstrating an association between two closely linked CTNNA3 gene SNPs and DA. These findings lend further support to the clinical relevance of these genotypes in predicting susceptibility to DA and the potential importance of catenins in the disease process.
Extensive literature exists on potential risk factors for childhood asthma. To the authors' knowledge, no investigators have yet attempted to disentangle the effects of those determinants within a single study setting. The authors aimed to evaluate the independent effects of 47 potential determinants (from the prenatal, perinatal, and childhood periods) of asthma development in children within the first 10 years of life. From a Canadian birth cohort of 26,265 children (1990-2002), a 2-stage case-control study was conducted. In the first stage, 20 controls per case were selected from 3 administrative databases. In the second stage, selected mothers were mailed questionnaires for assessment of additional determinants. Increased risks of childhood asthma were found for > or =1 previous diagnosis of bronchopulmonary disease and atopic dermatitis in the child, oxygen administration after birth, prescription of antibiotics within the first 6 months of life, male gender, asthma during pregnancy, use of antibiotics during pregnancy, maternal receipt of social aid, paternal asthma, and asthma in siblings. Protective effects included use of intranasal corticosteroids during pregnancy, having a wood-burning fireplace, having pets in the home prior to the index date, breastfeeding, and day-care attendance. This study allowed the authors to identify, within a single setting, the most influential determinants of childhood asthma among 47 predictors assessed for the prenatal, perinatal, and childhood periods.
Notes
Comment In: Am J Epidemiol. 2009 Jun 15;169(12):1532-3; author reply 1533-419433616
In a previous study, the authors assessed direct costs for occupational asthma (OA) in a random sample of eight to 10 accepted claims per year for OA between 1988 and 2002. Compensation for loss of income (CLI) was found to be significantly higher for men and for OA caused by low-molecular-weight agents.
To identify sociodemographic factors that modulate CLI, the dossier of each claimant in the previous study was re-examined.
Higher CLI costs were directly related to the duration of CLI (over which loss of income was reimbursed) (r=0.65). Costs of CLI were higher in patients 30 years of age or older at diagnosis, married subjects and individuals who were offered early retirement or were enrolled in an active interventional rehabilitation program. Higher CLI costs in men, but not in women, were associated with the following sociodemographic factors: older age, different rehabilitation program (early retirement and active program versus no specific program) and married status. Older age was found to be significant in the multivariate analysis performed for men. The cost of CLI was higher in workers with OA caused by low-molecular-weight agents. Although proportionally fewer men and younger workers were affected with OA caused by low-molecular-weight agents, the longer duration of CLI for this category of agent could explain the higher costs.
Higher costs for CLI were associated in men (but not women) with older age, married status and type of rehabilitation program (early retirement and active rehabilitation). Higher costs of CLI for OA caused by low-molecular-weight agents were associated with a longer duration of CLI per se, and not with sociodemographic factors.
Notes
Cites: Eur Respir J. 2002 Jun;19(6):1107-1312108864
Forty to 70 cases of occupational asthma due to sensitization to an agent present in the workplace are accepted each year by the Commission de la santé et de la sécurité du travail, the Quebec medicolegal agency.
In a random sample of eight to 10 accepted claims per year from 1988 to 2002, the direct costs of compensation for loss of income (CLI) and compensation for functional impairment (CFI), as well as the associations of these costs with selected variables, were assessed.
Mean costs (presented as Canadian dollars x10(3)) of CLI, CFI and total were 72.5, 11.7 and 92.8, respectively, while the median costs were 40.7, 7.6 and 61.3 for CLI, CFI and total, respectively. Median CLI costs were significantly higher in men than women (69.9 versus 13.1), workers aged 40 years or older versus those younger than 40 years (90.1 versus 27.4), workers with occupational asthma due to workplace exposure to low versus high molecular weight agents (51.2 versus 38.6), and workers taking inhaled steroids at diagnosis (92 versus 52) and reassessment (81 versus 35). Median CFI costs were also higher in those requiring retraining (10.4) and taking early retirement (61.8) than workers who stayed with the same employer but in a different job (5.4). Median CFI costs were significantly higher for individuals being treated with inhaled steroids at the time of diagnosis (14.0 versus 5.2) and reassessment (13 versus 6), and for those left with bronchial hyperresponsiveness (9.5 versus 0.8) related to forced expiratory volume in 1 s and forced expiratory volume in 1 s/forced vital capacity.
Age, sex, nature of occupational agent, treatment with inhaled steroids and type of rehabilitation all affect CLI, whereas lung function status at baseline and reassessment is related to CFI.
Notes
Cites: Eur Respir J. 2003 Oct;22(4):689-9714582924
Cites: Eur Respir J. 2007 May;29(5):889-9617182649
Cites: Can J Public Health. 2005 May-Jun;96(3):230-315913092
To explore one aspect of the external validity of the randomized controlled trial (RCT), specifically how being selected for inclusion in a trial and having participated has influenced the use and cost of asthma-related health services.
Services used by asthmatic users of inhaled corticosteroids (iCSTs) having previously participated in an RCT (TS, n = 46) were compared with individuals who had never participated (NS, n = 51).
TS were more likely to use higher (> or = 400 microg) daily doses of iCSTs than NS (OR, 3.3; 95% Cl, 1.1-8.3) but less likely to visit emergency departments (OR, 0.3; 95% Cl, 0.1-0.7). Total asthma-related costs did not differ significantly.
Subject differences may impede generalizing from RCTs to real life.
To assess the transportability of an existing diagnostic questionnaire model for the sensitization to laboratory animal (LA) allergens.
The model was externally validated in 414 Canadian animal health apprentices. Several approaches were used: (1) no adjustment; (2) recalibration of the intercept of the model; (3) re-estimation of the intercept and the regression coefficients of predictors; and (4) model revision, by excluding the existing predictor(s) and/or including new predictor(s). The bootstrapping procedure was done following the third and fourth methods. The calibration was assessed graphically and with the Hosmer-Lemeshow (HL) test. Discriminative properties were determined by the area under the receiver operating characteristic curve (ROC area).
When applied without adjustment, the model's discriminative ability was adequate (ROC area was 0.74 vs. the original ROC area of 0.76); the calibration was poor (HL test P0.10) and reasonable discrimination (ROC area ranged between 0.73 and 0.75). The refitted and revised model showed a good internal validity (correction factor from the bootstrapping procedure was more than 0.90).
Once updated, the diagnostic model is valid and can be applied with reasonable performance in an animal health apprentice setting.
Clinicians are faced with subjects complaining of work-related respiratory symptoms (WRS) without any evidence of asthma. We sought to assess the prevalence of subjects with WRS without asthma in a cohort of workers referred for possible work-related asthma (WRA) as well as compare the characteristics and the work environment of subjects with WRS to subjects with WRA.
A prospective observational study of workers referred for possible WRA over a 1-year period. Detailed medical and occupational questionnaires were administered. Pulmonary function tests as well as specific-inhalation challenges were performed.
One hundred twenty workers were investigated. Fifty-one had WRA while 69 had WRS. The type and the severity of the respiratory symptoms were similar in both groups, except for wheezing which was more frequently reported in subjects with WRA (32 (62.7%)) than in subjects with WRS (16 (23.2%)) (P
Diisocyanates are a common cause of occupational asthma, but risk factors are not well defined. A case-control study was conducted to investigate whether genetic variants of antioxidant defense genes, glutathione S-transferases (GSTM1, GSTT1, GSTM3, GSTP1), manganese superoxide dismutase (SOD2), and microsomal epoxide hydrolase (EPHX1) are associated with increased susceptibility to diisocyanate-induced asthma (DA). The main study population consisted of 353 Caucasian French-Canadians from among a larger sample of 410 diisocyanate-exposed workers in three groups: workers with specific inhalation challenge (SIC) confirmed DA (DA(+), n = 95); symptomatic diisocyanate workers with a negative SIC (DA(-), n = 116); and asymptomatic exposed workers (AW, n = 142). Genotyping was performed on genomic DNA, using a 5'-nuclease PCR assay. The SOD2 rs4880, GSTP1 rs1695, and EPHX1 rs2740171 variants were significantly associated with DA in both univariate and multivariate analyses. In the first logistic regression model comparing DA(+) and DA(-) groups, SOD2 rs4880, GSTM1 (null), GSTP1 rs762803, and EPHX1 rs2854450 variants were associated with DA (p = 0.004, p = 0.047, p = 0.021, p
Identification of clinically significant psychological distress and psychiatric morbidity by examining quality of life in subjects with occupational asthma.
Division of Chest Medicine, Research Center, Department of Chest Medicine, Hôpital du Sacré-Cœur de Montréal, 5400 Gouin West, Montréal, Québec, H4J 1C5, Canada.
The Juniper Asthma Specific Quality of Life Questionnaire (AQLQ(S)) is a questionnaire that allows measurement of disease specific quality of life. We wanted to examine correlations between the (AQLQ(S)) general and different subscale scores and both psychiatric morbidity and levels of psychological distress in individuals with occupational asthma (OA) and to determine if results in the emotional function subscale allow identification of individuals with clinically significant psychological distress or current psychiatric disorders.
This was a cross-sectional study of individuals with OA who were assessed during a re-evaluation for permanent disability, after they were no longer exposed to the sensitizing agent. Patients underwent a general sociodemographic and medical history evaluation, a brief psychiatric interview (Primary Care Evaluation of Mental Disorders, PRIME-MD) and completed a battery of questionnaires including the AQLQ(S), the St-Georges Respiratory Questionnaire (SGRQ), and the Psychiatric Symptom Index (PSI).
There was good internal consistency (Cronbach alpha = 0.936 for the AQLQ(S) total score) and construct validity for the AQLQ(S) (Spearman rho = -0.693 for the SGRQ symptom score and rho = -0.650 for the asthma severity score). There were medium to large correlations between the total score of the AQLQ(S) and the SGRQ symptom score (r = -.693), and PSI total (r = -.619) and subscale scores (including depression, r = -.419; anxiety, r = -.664; anger, r = -.367; cognitive disturbances, r = -.419). A cut-off of 5.1 on the AQLQ(S) emotional function subscale (where 0 = high impairment and 7 = no impairment) had the best discriminative value to distinguish individuals with or without clinically significant psychiatric distress according to the PSI, and a cut-off of 4.7 best distinguished individuals with or without a current psychiatric disorder according to the PRIME-MD.
Impaired quality of life is associated with psychological distress and psychiatric disorders in individuals with OA. Findings suggest that the AQLQ(S) questionnaire may be used to identify patients with potentially clinically significant levels of psychological distress.
