Cardiovascular Risk and Firefighting

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Cardiovascular Risk and Firefighting

• Dr Ian Griffiths
• Consultant Occupational Physician
• Nottingham University Hospitals
• March 2009

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Content

• Case presentation
• Cardiovascular disease in Firefighters how much
  of a problem is it?
• What might cause cardiovascular disease in
  Firefighters?
• What can we do to reduce any risks?

3
Case Study

• 41 year old male FF
• Minor chest discomfort April 08
• 3 days later, severe chest pain
• In hospital 7 days
• Inferior ST elevation MI

4
Risk factors

• Male (RR 3.1)
• Ex smoker aged 20
• Cholesterol 5.6mmol/L
• No family history
• Exercise 5 miles of walking or cycling 2 or 3
  days a week
• Not overweight
• Lundblad et al, Biomed Central, 2008

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Treatment

• Clot busted by paramedics
• Aspirin 75mg OD
• Clopidogrel 75mg OD
• Atorvastatin 40mg OD
• Ramipril 10mg OD
• Bisoprolol 2.5mg OD
• 12 sessions in cardiac rehab

6
Occupational Health Involvement

• Seen July 08
• Return to Work after Cardiac illness, British
  Heart Foundation 09/98 states return to full
  activity including work in 4-6 weeks after MI
• Well, cheerful, symptom free, returned to all
  activities

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Job

• WT crew manager
• Shifts starting 0700 1900
• No LGV licence
• Likes job

8
Examination findings

• Optimistic and positive
• Realistic
• Not overweight
• P 48 regular
• BP 128/76
• No signs of heart failure

9
Advice to management July 08

• Fit for any work except firefighting
• Await info from specialist (asking specific
  questions)
• Needs careful thought on risks of returning to
• Firefighting
• Shift work

10
Coronary Artery anatomy

11
Reply from specialist October 08

• Angiogram May 08
• Left main disease free
• LAD modest stenosis in mid vessel, about 50
• Circumflex plaque disease
• RCA dominant, modest stenosis in mid vessel,
  presumably the cause of the infarct
• Small area hypokinesia inferior wall

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What constitutes significant narrowing?

• Significant flow limitation occurs when there is
  a 50 reduction in diameter
• Flow limitation sufficient enough to produce
  effort angina does not usually occur until there
  is greater than 70 reduction in luminal diameter
• Medical and Occupational Evidence for Recruitment
  and Retention in the Fire and Rescue Service,
  ODPM, Sept 2004

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Reply from specialist October 08

• Best managed medically
• Long-term outlook good because of preserved LV
  function and minor atheroma
• Needs aggressive medical therapy in light of
  cardiac event aged 40

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Guidance from the Bible

• In asymptomatic individuals already in service,
  full post-infarction assessment, including stress
  testing is required.
• A negative stress test should include no
  symptoms, no significant ST changes and the
  individual should have completed Stage III (at
  least 9 minutes) of the Bruce Protocol with no
  anti-anginal therapy. Any doubt about the stress
  test should lead to angiography.
• Medical and Occupational Evidence for Recruitment
  and Retention in the Fire and Rescue Service,
  ODPM, Sept 2004

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Advice to management Oct 08

• Given reported levels of exercise, hed have no
  difficulty in undertaking tasks demanded of him
  as a FF
• However, need to consider risks of further
  cardiac event associated with FFing and/or shift
  work

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Subsequent Developments

• Meeting with DCFO late Nov 08
• Risks / benefits of RTW discussed
• Limitations of research being mostly from USA
  apparent

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Subsequent Developments (2)

• DCFO agrees RTW Jan 09
• Risk to colleagues the public adequately
  managed
• Risks to you from shift work and emergency
  response are present
• Asked to agree content of letter by signing
  returning it

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Discussion

• Do UK FFs have an excess of CVD?
• US data showing numbers of MIs at work
• Mechanisms of CVD in FFs
• Preventative strategies

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Coronary Artery Disease
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Why might MIs occur more often in FFs?

• Does Fire fighting-
• Cause CVD to develop?
• Cause plaque rupture to occur?
• Cause arrhythmias in normal hearts?

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Deaths from Heart Disease in FFs

• Little data on extent of CVD in UK Firefighters
• No excess noted in data from Office of
  Population, Censuses and Surveys
• No other data that I could find showing excess

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Deaths from Heart Disease in UK FFs

• The 36 deaths (30 of total) attributed to
  natural causes were generally heart attacks,
  which took place either at operational incidents
  or shortly afterwards, or on fire service
  premises while on duty. These figures do not
  include firefighters who died whilst off duty
  from heart attacks.
• Labour Research Dept. In the Line of Duty
  Firefighter Deaths in the UK Since 1978, Nov
  2008.

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Deaths from Heart Disease in US FFs

• Heart disease causes 45 of deaths of U.S. FFs
  whilst on duty
• Police officers 22
• Emergency Medical Service Workers 11
• All workers 15
• Kales et al, NEJM, 2007

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Deaths from Heart Disease in US Fire Fighters
cont.

• Risk of death compared to that during
  nonemergency duties Time
• Fire suppression 12.1 136 (1-5)
• Alarm response 2.8 14.1 (4-9)
• Alarm return 2.2 10.5 (7-15)
• Physical training 2.9 6.6 (8)
• Kales et al, NEJM, 2007

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Why should FFing cause heart disease?

• Smoke chemical exposure
• Irregular physical exertion
• Heat stress
• Shift work
• High prevalence of CVS risk factors
• Psychological stressors

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Chemical Exposures in FFing

• CO
• Oxides of nitrogen
• HCl
• Isocyanates
• Acetaldehyde
• PAHs
• Benzene

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Physiological Demands of FFing

• HR reaches 70 80 of age-predicted maximums
  within 1 minute of arriving at an active fire
• HR sustained at 85 100 until fire is
  extinguished
• Guidotti, Int Arch Occ Env Health, 1992

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Shift work CVD

• Fairly strong evidence for association
• 45-55 yr olds RR 1.6 for men, 3.0 for women
• Job strain no different in cases controls
• Mechanism unclear
• Knutsson et al, Occ Env Med 1999

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Do workers with CVD or risk factors stop shift
work?

• 7037 female nurses (5038 worked shifts, 1999 days
  only)
• Data collected in 2000-02, and again in 2004, on
• Known MI, angina or high BP
• High cholesterol
• Obesity
• Diabetes

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Do workers with CVD or risk factors stop shift
work? (2)

• Among shift workers, likelihood of leaving
  organisation 1.83 (1.01 3.32) times higher if
  had diabetes c.f. no diabetes
• 2.21 (1.12 4.39) times higher if had 3-4 risk
  factors c.f. no risk factors
• BUT similar rates for leaving for day workers
• Hence healthy worker effect does not cause bias
• Kivimaki M et al, Scand J Work, Env health,
  June 2006

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Mechanism of CVD in shift workers

• 1543 young adults examined (age 24-39) as part of
  Cardiovascular Risk in Young Finns study
• Measured thickness of common carotid artery
  intima/media
• Puttonen et al, Atherosclerosis, Jan 2009

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Mechanism of CVD in shift workers cont.
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Mechanism of CVD in shift workers cont.

• In men, shift work associated with a higher mean
  thickness of common carotid artery intima/media
  and 2.2 (1.2 4) fold risk of carotid plaque
• Puttonen et al, Atherosclerosis, Jan 2009

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Stress and CVD

• Whitehall II
• Chronic work stress associated with CVD
• Association was stronger among participants aged
  lt 50 (RR 1.68, 95 CI 1.172.42)
• Chandola et al, European Heart Journal 2007

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Can we do anything about those at risk?

• In 2005, 115 FFs died on duty in USA
• 48 of fatalities were MIs
• Mean age 47
• Dept. of Homeland Security target to reduce FF
  fatalities by 50 within 10 years
• Gaetano et al, AAOHN Journal, Feb 2007

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Health Surveillance for US FFs

• Volunteer FFs at higher risk of MI attributed to
  stress and overexertion
• Virtually no standardised requirements for CV
  fitness in volunteers, even as recruits
• Gaetano et al, AAOHN Journal, Feb 2007

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Health Surveillance for US FFs cont.

• 1998 2003 1,458 volunteer FFs and emergency
  medical services personnel had at least 1 health
  surveillance examination
• 45 years or over get non fasting cholesterol
  HDL measured Framingham Risk Score calculated
• 658 abnormal findings
• Gaetano et al, AAOHN Journal, Feb 2007

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Health Surveillance for US FFs cont.
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Cardiovascular risk

• 315 staff evaluated for CVD risk
• 52 (17) had scores of 9 (substantial risk)
• 39 of those saw GP or cardiologist
• 1 had CABG, 2 had angioplasties, 14 had
  antihypertensive drugs, 9 begun lipid lowering
  medication, 13 no action

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Obesity in FFs

• Fireman sacked for being 'too fat'
  after failing three-month test to lose
  weight Daily Mail, 15/1/09

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Obesity in FFs (2)

• 332 Massachusetts FFs BMIs compared in 1996
  2001
• Mean BMI changed from 29 to 30 kg/m2
• Prevalence of obesity rose from 35 to 40 (p lt
  0.0001)
• Morbid obesity increased 4 fold (0.6 to 2.4, p
  lt 0.0001)
• Soteriades et al, Obesity Research, Oct 2005

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Obesity in FFs (3)

• Obese FFs more likely to have high BP
• (p 0.03)
• Normal weight FFs gained 1.1lb, c.f FFs with BMI
  gained 1.9 lb per year
• Soteriades et al, Obesity Research, Oct 2005

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Summary

• Little data on CVD in UK Firefighters
• Advice given currently has to use existing
  guidance and risk assessment principles
• Plenty of scope for OH and Fitness depts to
  measure and address existing risk factors
  undertake research

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Any questions?