Publications

BACKGROUND

There is a well-established association between inhalational exposure to silica and autoimmune disease. We recently observed an outbreak of silica-related autoimmune disease among synthetic stone construction workers with silicosis referred for lung transplantation assessment.

AIMS

To characterize the rheumatologic complications in silicosis within these highly exposed, clinically well-characterized patients.

METHODS

We systematically reviewed data from all cases of silicosis due to synthetic stone dust referred to our pulmonary institute for lung transplant assessment, which represents the national centre for all such referrals. In addition to silicosis-specific data, we extracted data relevant to the clinical and serological manifestations of autoimmune diseases present in these patients.

RESULTS

Of 40 patients in our advanced silicosis national data, we identified nine (23%) with findings consistent with various autoimmune diseases. Among these nine, three also had findings consistent with pulmonary alveolar proteinosis. Based on an expected autoimmune disease prevalence of 3% (based on the upper-end estimate for this group of diseases in European international data), the proportion of disease in our group represents a >7-fold excess (prevalence ratio 7.5; 99% confidence interval 2.6-16.7).

CONCLUSIONS

These cases underscore the strong link between silicosis and multiple distinct syndromes of autoimmune diseases. Vigilance is warranted for the recognition of autoimmune complications in persons with known silicosis; so too is consideration of the occupational exposure history in persons presenting with manifestations of autoimmune disease.

OBJECTIVES

To examine trends in tuberculosis (TB) incidence and to compare demographic and clinical characteristics of nursing home (NH) residents and community-dwelling older adults.

DESIGN

Prospective TB surveillance.

SETTING

TB cases reported in California from 2000 to 2009.

PARTICIPANTS

TB patients aged 65 and older.

MEASUREMENTS

Trends in TB incidence per 100,000 population were assessed using Poisson regression. Demographic and clinical characteristics were compared using the chi-square or Wilcoxon rank-sum test. Among NH residents, risk factors for death during TB treatment were identified using logistic regression.

RESULTS

From 2000 to 2009, TB incidence rates decreased significantly, from 15.9/100,000 to 8.4/100,000 (-44%, 95% confidence interval (CI) = -66% to -7%) for NH residents and from 21.2/100,000 to 15.0/100,000 (-27%, 95% CI = -29% to -24%) for community-dwelling older adults. Overall, 211 TB cases among NH residents and 6,518 cases among community-dwelling older adults were reported. NH residents were more likely than community-dwelling older adults to be older (median age 81 vs 75, P < .001), have a negative acid-fast bacilli sputum smear and positive culture (37% vs 28%, P < .001), and die while undergoing TB treatment (44% vs 14%, P < .001), and were less likely to have a positive tuberculin skin test (TST) (28% vs 44%, P < .001) and have TB care provided by a health department (20% vs 59%, P < .001). In multivariable analysis, NH residents who had a positive TST were less likely to die while undergoing TB treatment (odds ratio = 0.39, 95% CI = 0.16-0.96).

CONCLUSION

TB incidence rates were lower, and reductions in incidence were greater among NH residents; community-dwelling older adults had higher TB rates and smaller reductions in incidence. Interventions that promote timely detection and treatment of TB infection and disease may be needed to reduce morbidity and mortality among NH residents.