Thousands of firefighters ... have sued the maker of the sirens, contending they caused hearing loss.
A study ... [Dr Clark] published in 2005 concluded that 'firefighters are not at risk for occupational noise-induced hearing loss, even though they work nonstandard shifts and are occasionally exposed to high levels of noise.'
The siren manufacturer, Federal Signal Corp., told a court the study 'directly refutes plaintiffs' argument that siren noise exposure causes hearing loss in firefighters.'
What the study didn't mention was that Dr. Clark was a paid expert for the company helping it with its litigation at the same time as he was doing his research. Not only that, but the company gathered data that were the basis of the study.
Readers of Dr. Clark's study, which ran in Ear & Hearing Journal, were told only that the researcher 'has provided consulting services for manufacturers of emergency firefighting equipment.' There was no mention that such a manufacturer was being sued for causing hearing loss.
Dr Clark has also studies hearing loss in railroad workers.
Union Pacific railroad ... was defending a slew of suits claiming trainmen were losing their hearing from noise.
In 1989, ... [Dr Clark] published a peer-reviewed article concluding that 'trainmen are not typically exposed to hazardous occupational noise.'
After its publication, cases began to be settled on less-generous terms, according to affidavits from rail workers and the railroad. They were settled for 80% less, on average, than before the Clark study appeared.
The journal that published the trainmen report, called Laryngoscope, didn't disclose that Dr. Clark was consulting for Union Pacific. Dr. Clark says it didn't require such disclosure. Laryngoscope says it doesn't know what its disclosure policy was in the late '80s.
[Dr Clark] also ran a 'hearing hotline' for Union Pacific workers that, among other things, counseled them on results of their hearing tests.
To run the railroad's hearing hotline, Union Pacific paid $850,000 to a partnership of Dr. Clark and his co-author of the railroad hearing-loss study, according to a deposition Dr. Clark gave in Cook County, Ill., Circuit Court.
Dr Clark also studied hearing loss in miners.
In 1997, the U.S. Mine Safety and Health Administration was considering tougher noise guidelines. An industry group called the National Mining Association hired Dr. Clark to do a critical analysis of another federal body's noise data. He testified before the mine agency against tougher guidelines.
Two years later, Dr. Clark published a study concluding that miners did not have significant occupational hearing loss. The study was done "at the request of the National Mining Association," he acknowledged in the article. He didn't mention that the association had paid him as a consultant.
This is a reminder that conflicts of interest affecting medical researchers are not limited to those due to their financial relationships with pharmaceutical, biotechnology, and device manufacturers. In this case, the conflicts were generated by financial relationships a medical researcher had with a manufacturer of sirens, a railroad, and a mining trade association.
In all cases, though, such conflicts throw doubt on the interpretation of the resulting research. One wonders whether conclusions of research studies done by researchers with conflicts, particularly conflicts that are not clearly disclosed, may have been influenced by the relevant financial relationships, and thus to what extent the research should not be trusted. The questions raised by such conflicts are almost impossible to answer unless one can find clearly unconflicted research that addressed the same question.
This just expands the rationale for what we have said before: pervasive conflicts of interest in health care make figuring out what is best for patients even harder. And this just strengthens our previous argument that physicians, other health care professionals, and leaders of health care organizations should rid themselves of conflicts of interest that might influence their professional, academic, or research work on behalf of patients or public health.