Autoimmune Mortality Higher Among Some Benign Professions

By Neil Osterweil, Senior Associate Editor, MedPage Today
Reviewed by _Robert Jasmer, MD; Associate Clinical Professor of Medicine,
University of California, San Francisco _
(http://www.medpagetoday.com/reviewer.cfm?reviewerid=55)
September 28, 2007
_Add Your Knowledgeâ„¢_
(http://www.medpagetoday.com/Rheumatology/GeneralRheumatology/dh/6818#ayk) _Additional General Rheumatology Coverage_
(http://www.medpagetoday.com/Rheumatology/GeneralRheumatology/)

SEATTLE, Sept. 28 -- There is something about farming, nursing, and teaching
that seems to predispose those who work at these professions to death from
systemic autoimmune diseases, reported investigators here.
Action Points
* Explain to patients that the study looked at associations of
occupations and autoimmune mortality only and could not determine causality.

* Further study of specific jobs and workplace exposures to chemicals,
infectious organisms, and so forth is needed to determine whether specific
exposures confer increased risk of death from an autoimmune condition.

Other occupations consistently associated with death from autoimmune disease
included textile machine operation, mining machine operators, painting and
decorating, reported Laura S. Gold, M.S.P.H., of the Fred Hutchison Cancer
Center, and colleagues, in the October issue of Arthritis & Rheumatism.
These findings emerged from a case-control review of U.S. death certificates
from 26 states from 1984 to 1998, with the authors flagging any cases that
listed a systemic autoimmune disease such as rheumatoid arthritis, systemic
lupus erythematosus, or systemic sclerosis as a cause.
The study suggested that occupations involving exposure to chemicals or
animals, or both, might put workers at increased risk for autoimmune conditions,
as may some -- but not all -- careers involving public exposure.
For example, nursing and teaching were associated with increased risk, but
food preparation and handling was associated with a lower than average risk of
mortality from autoimmune conditions.
The investigators also included in their analyses disorders with suspected
but not proven autoimmune origin, such as unspecified connective tissue
disorders.
For each case five controls matched by age, gender, race, year of death and
geographic region were also selected.
The investigators determined the longest-held occupation of each case using
the "usual occupation" box from death certificates. They also looked at
specific occupational exposures such as pesticides and fertilizers in farming, and
the use of benzene and solvents in manufacturing. Jobs involving significant
exposure to other people, such as nursing, teaching, and restaurant work,
were also examined.
They identified 36,178 deaths attributed to RA, 7,241 to lupus, 5,642 to
systemic sclerosis, and 4,270 to other autoimmune disease.
The researchers found that "a broad array of occupations was associated with
death from systemic autoimmune diseases, including several of a priori
interest," they wrote.
The odds ratio for death from systemic autoimmune disease among farmers was
1.3 (95% confidence interval 1.2 to 1.4). When they looked at specific
diseases, only RA was significantly associated with death among farmers,
particularly for farmers who worked with crops rather than with livestock.
Industrial occupations significantly associated with autoimmune disease
mortality included mining machine operation (odds ratio 1.3, 95% CI 1.1 to 1.5),
miscellaneous textile machine operators (odds ratio 1.2, 95% CI 1.0 to 1.4),
and hand painting, coating, and decorating (odds ratio 1.8, 95% CI 1.0 to
2.9).
Certain public exposure occupations were also associated with increased risk
of death from autoimmune conditions. For example, elementary school teaching
was associated with an odds ratio for death from any autoimmune disease of
1.23 (95% CI, 1.16 to 1.30), special education teaching was associated with
and odds ratio of 1.92 (95% CI 1.10 to 3.17), and nursing was associated with
an odds ratio of 1.09 (1.01 to 1.17).
"These occupations were also significantly associated with death from the
specific autoimmune diseases examined," the authors noted. For example,
occupational exposure to the public was associated slightly with death from lupus
(odds ratio 1.1, 95% CI 1.0-1.2), and exposure to animals was associated with a
28% increase in risk of death from rheumatoid arthritis.
But other public exposure jobs were associated with decreased risk for death
from autoimmune diseases, including butchers, waiters/waitresses, and cooks
(except short-order cooks), the authors noted.
In an analysis by age, they found that the higher-risk occupations and
exposures were also present among those people who were past typical retirement
age at the time of death, "implying that the occupational exposures were
involved in a chronic pathogenic process leading to either disease incidence or
slow progression of existing autoimmunity," they wrote.
They suggested that the association between nursing, teaching, and other
jobs with high public exposure may be related to exposure to multiple infectious
agents that could trigger autoimmunity. In addition, because teachers and
nurses tend to have good health insurance coverage, deaths from autoimmune
diseases may be more frequently captured in vital records than deaths among
others with public exposure but less reliable health coverage, such as waiters
and waitresses, they suggested.
"The size of our study allowed us to estimate associations between specific
occupations and death from autoimmune diseases and to generate hypotheses
that will be useful as starting points for future studies in this area," the
authors concluded.
Their study was limited by a tendency to underreport autoimmune disorders on
death certificates, and by potential biases associated with the availability
of health insurance.
The study was supported by grants from the National Institute of
Environmental Health Sciences and by the Intramural Research Program of the National
Cancer Institute. There were no reported author conflicts of interest.
_Additional General Rheumatology Coverage_
(http://www.medpagetoday.com/Rheumatology/GeneralRheumatology/)

Primary source: Arthritis & Rheumatism
Source reference:
Gold LS et al. _"Systemic Autoimmune Disease Mortality and Occupational
Exposures."_ (http://www3.interscie
nce.wiley.com/cgi-bin/abstract/116324692/ABSTRACT) Arthritis Rheum 2007; 56(10): 3189-3201.

CPAP Reverses Atherosclerotic Effects of Sleep Apnea

By Crystal Phend, Staff Writer, MedPage Today
Reviewed by _Robert Jasmer, MD; Associate Clinical Professor of Medicine,
University of California, San Francisco _
(http://www.medpagetoday.com/reviewer.cfm?reviewerid=55)
September 28, 2007
_Add Your Knowledgeâ„¢_
(http://www.medpagetoday.com/Psychiatry/sleepdisorders/dh/6825#ayk) _Additional Sleep Disorders Coverage_
(http://www.medpagetoday.com/Psychiatry/sleepdisorders/)
SAO PAULO, Brazil, Sept. 28 -- Treatment of obstructive sleep apnea with
continuous positive airway pressure reverses early signs of atherosclerosis,
researchers here found.
Action Points
* Explain to interested patients that the study affirms a causal link
between obstructive sleep apnea and atherosclerosis.

* Inform patients that CPAP may help reverse the cardiovascular risk
caused by severe sleep apnea, but further study is needed to show it prevents
heart attack and other outcomes.

In a carefully controlled, randomized trial, CPAP therapy reduced carotid
intima-media thickness 9% over four months and improved arterial stiffness 10%
among men with severe sleep apnea reported in the first October issue of the
American Journal of Respiratory and Critical Care Medicine.
These were "remarkable" changes as great as improvements seen in statin
trials over six months to a year, said Luciano F. Drager, M.D., of the University
of São Paulo here, and colleagues.
Furthermore, the findings provide the first solid evidence of the
long-suspected causal link between sleep apnea atherosclerosis, commented T. Douglas
Bradley, M.D., and Dai Yumino, M.D., both of the Center for Sleep Medicine and
Circadian Biology at the University of Toronto, Canada, in an accompanying
editorial.
"Because obstructive sleep apnea affects approximately 10% of the adult
population," they wrote, "these results may have important public health
implications for prevention of atherosclerotic diseases."
The link has been difficult to prove because the majority of sleep apnea
patients have other risk factors for atherosclerosis, including obesity,
hypertension, high cholesterol levels, insulin resistance, and hyperglycemia, they
said.
Of the 400 consecutive men who had more than 30 apnea and hypopnea events
per hour during a polysomnographic sleep test at the Brazilian center, the
researchers excluded all but 24 for atherosclerosis risk factors.
The study included only treatment-naïve men 60 or younger with a body mass
index no greater than 35 kg/m2 and no diabetes, hypertension, cerebrovascular
or heart disease, renal failure, smoking history, or chronic use of any
medication.
These participants were randomly assigned to CPAP or no treatment for four
months.
On CPAP therapy, the average apnea-hypopnea index dropped to 4.5 events per
hour and early vascular markers of atherosclerosis fell as well.
Carotid intima-media thickness improved significantly from baseline to four
months in the CPAP group (707 versus 645 µm, P=0.04) whereas it got slightly
worse in the control group (732 versus 740 µm). The overall difference
between the groups was significant (P=0.02).
Arterial stiffness as measured by carotid-to-femoral artery pulse-wave
velocity was unchanged in the control group (10.1 versus 10.3 m/s) but decreased
significantly in all CPAP-treated patients (mean 10.4 versus 9.3 m/s,
P<0.001). Again, the CPAP group improved significantly compared with controls
(P<0.001).
The inflammatory marker C-reactive protein likewise improved only in the
CPAP group (3.7 versus 2.0 mg/L, P=0.001, compared with 3.1 versus 3.3 mg/L for
controls, P=NS) with a significant difference between groups in favor of
CPAP (P<0.001).
The sympathetic activation marker catecholamine showed the same pattern of
improvement in the CPAP group (365 versus 205 pg/mL, P<0.001) but not the
control group (362 versus 357 pg/mL, P=NS) for an overall significant difference
favoring CPAP (P<0.001).
No carotid plaque was observed in any participant, as expected because of
the strict exclusion criteria. Carotid diameter did not change significantly
with CPAP, likely because of the short study duration, the researchers said.
"These findings were all the more remarkable because there was no concurrent
change in weight, lipid levels, or blood pressure," Drs. Bradley and Yumino
said.
Early detection of atherosclerosis and subsequent therapeutic intervention
can "significantly alter the natural course of cardiovascular disease,"
suggesting that the findings do have clinical implications, Dr. Drager and
colleagues said.
However, the small sample size and highly selected patient population in the
study may limit applicability of the findings, Drs. Bradley and Yumino said.

Before sleep apnea "can take its place with traditional atherogenic factors
as a target for risk reduction, large-scale randomized trials that will
determine whether treatment of obstructive sleep apnea prevents ischemic
cardiovascular and cerebrovascular events should be undertaken," the editorialists
wrote.
Therefore, it is premature to recommend apnea screening and CPAP treatment
as a strategy to prevent atherosclerosis, the editorialists cautioned.
The study was supported by the Fundação de Amparo à Pesquisa do Estado de
São Paulo, Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico, and
the E.J. Zerbini Foundation. All the CPAP machines were provided by
Respironics, a manufacturer of CPAP devices.
The researchers and Dr. Bradley reported no conflicts of interest. Dr.
Yumino reported receiving support from an unrestricted research fellowship from
Respironics.
_Additional Sleep Disorders Coverage_
(http://www.medpagetoday.com/Psychiatry/sleepdisorders/)

Primary source: American Journal of Respiratory and Critical Care Medicine
Source reference:
Drager LF, et al "Effects of Continuous Positive Airway Pressure on Early
Signs of Atherosclerosis in Obstructive Sleep Apnea" Am J Respir Crit Care Med
2007; 176: 706-712.

Additional source: American Journal of Respiratory and Critical Care Medicine
Source reference:
Yumino D, Bradley TD "Pathogenesis of Atherosclerosis: Is Obstructive Sleep
Apnea the New Kid on the Block?" Am J Respir Crit Care Med 2007; 176:
634-635.
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