Community-acquired pneumonia: smoking, increasing age and weight-gain increase the risk

Clinical bottom line (level 1b)

  1. 1% of men aged over 44 developed a community-acquired pneumonia in a 6 year period.
  2. The risk was increased with
    • increasing age
    • current smoking
    • previous smoking within 10 years
  3. 0.4% of women aged 27 to 44 developed a community-acquired pneumonia over a 2 year period.
  4. The risk was increased with
    • current smoking
    • excessive weight gain
    and reduced with increasing physical exercise.
Baik et al: Archives of Internal Medicine 2000; 160 : 3082-3088
Expires October 2003

The study

Prospective cohort study with blinded outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting:

104491 patients 26429 men aged 44 to 79 from the Health Professionals Follow-up study, and 78062 women aged 27 to 44 from the Nurses' Health Study II.

Excluded if
  • pneumonia not confirmed by medical records or on subsequent questionnaires
  • pneumonia occured in hospital
  • diabetes mellitus
  • asthma
  • cancer
  • cardiovascular disease


    Factors studied:
  • age, cigarette smoking, body mass index, physical activity, alcohol intake
  • current smoking
  • current smoking > 25 cigarretes per day
  • smoked within last 10 years
  • current smoking
  • weight change since aged 18; 40 kg or more

    Participants were surveyed by biennial mailed questionnaires.

    Multiple logistic regression analyses were performed to adjust for confounding factors.

    100% followed for men 6 years; women 2 years
    Outcomes studied:
  • men: pneumonia from medical records
  • women: pneumonia from self-report

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    men: pneumonia 6 years 290/26429 1.1%
    (1.0% to 1.2%)    		 91
    (82 to 103)
    women: pneumonia 2 years 305/78062 0.39%
    (0.35% to 0.43%)    		 260
    (230 to 290)

    prognostic factor for
    men: pneumonia     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    current smoking men 6 years; women 2 years 1.46
    (1.00 to 2.14)     		250
    (100 to -)
    current smoking > 25 cigarretes per day men 6 years; women 2 years 2.54
    (1.40 to 4.59)     		76
    (32 to 290)
    smoked within last 10 years men 6 years; women 2 years 1.56
    (1.04 to 2.33)     		210
    (88 to 2900)

    prognostic factor for
    women: pneumonia     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    current smoking men 6 years; women 2 years 1.55
    (1.15 to 2.10)     		520
    (260 to 1900)
    weight change since aged 18; 40 kg or more men 6 years; women 2 years 2.13
    (1.38 to 3.29)

    Comments

    1. The risk of pneumonia rose with increasing age in men (compared with 45 or younger):
      • aged 55-59: RR 1.87
      • aged 60-64: RR 2.75
      • aged 65-69: RR 2.98
      • aged 70 or more: RR 4.19
    2. Increased physical activity reduced the risk of pneumonia in women: highest quintile v. lowest: RR 0.66 (95% CI: 0.46 to 0.95)

    Citation

    1. Baik I, Curham GC, Rimm EB, et al: a prospective study of age and lifestyle factors in relation to community-acquired pneumonia in US men and women. Archives of Internal Medicine 2000; 160 : 3082-3088
    Search Terms: ?
    Contributor: Chris Ball, October 2001
    Reviewer:

    Clinical Question.
    Patient healthy
    Intervention or Exposure risk factors: smoking, weight gain, exercise, age
    Outcome community-acquired pneumonia
    		•