COPD and the risk of tuberculosis--a population-based cohort study.
BACKGROUND
Both chronic obstructive pulmonary disease (COPD) and tuberculosis (TB) primarily affect the lungs and are major causes of morbidity and mortality worldwide. COPD and TB have common risk factors such as smoking, low socioeconomic status and dysregulation of host defence functions. COPD is a prevalent co-morbid condition, especially in elderly with TB but in contrast to other diseases known to increase the risk of TB, relatively little is known about the specific relationship and impact from COPD on TB-incidence and mortality.


RESULTS
All individuals > or = 40 years of age, discharged with a diagnosis of COPD from Swedish hospitals 1987-2003 were identified in the Swedish Inpatient Register (n = 115,867). Records were linked to the Swedish Tuberculosis Register 1989-2007 and the relative risk of active TB in patients with COPD compared to control subjects randomly selected from the general population (matched for sex, year of birth and county of residence) was estimated using Cox regression. The analyses were stratified by year of birth, sex and county of residence and adjusted for immigration status, socioeconomic status (SES) and inpatient co-morbidities previously known to increase the risk of TB. COPD patients had a three-fold increased hazard ratio (HR) of developing active TB (HR 3.0 (95% confidence interval 2.4 to 4.0)) that was mainly dependent on an increased risk of pulmonary TB. In addition, logistic regression estimates showed that COPD patients who developed active TB had a two-fold increased risk of death from all causes within first year after the TB diagnosis compared to the general population control subjects with TB (OR 2.2, 95% confidence interval 1.2 to 4.1).


CONCLUSIONS
This population-based study comprised of a large number of COPD patients shows that these patients have an increased risk of developing active TB compared to the general population. The results raise concerns that the increasing global burden of COPD will increase the incidence of active TB. The underlying contributory factors need to be disentangled in further studies.
Inghammar
Malin
M
Section for Infection Medicine, Department of Clinical Sciences Lund, Lund University, Lund University Hospital, Lund, Sweden. malin.inghammar@med.lu.se
Ekbom
Anders
A
Engström
Gunnar
G
Ljungberg
Bengt
B
Romanus
Victoria
V
Löfdahl
Claes-Göran
CG
Egesten
Arne
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003625:Data Collection; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000453:epidemiology; D012044:Regression Analysis; D012306:Risk; D013548:Sweden / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology / Q000209:etiology* / Q000401:mortality
Int J Tuberc Lung Dis. 2002 Aug;6(8):662-5
12150476
Eur Respir J. 1996 Oct;9(10):2031-5
8902463
Pediatr Infect Dis J. 2000 Mar;19(3):215-8
10749462
Am J Respir Crit Care Med. 2000 Apr;161(4 Pt 2):S221-47
10764341
Int J Epidemiol. 2005 Aug;34(4):914-23
15914505
Respir Med. 1998 Dec;92(12):1337-45
10197227
Am J Respir Crit Care Med. 2009 Sep 1;180(5):475-80
19542475
Arch Intern Med. 2007 Feb 26;167(4):335-42
17325294
Int J Tuberc Lung Dis. 2006 May;10(5):490-8
16704029
N Engl J Med. 2008 Nov 27;359(22):2355-65
19038881
Science. 1997 Jan 3;275(5296):77-9
8974396
Chest. 2008 Jul;134(1):46-53
18403661
Ann Intern Med. 1976 Mar;84(3):261-5
1259260
Eur J Epidemiol. 2009;24(11):659-67
19504049
Eur Respir J. 2009 May;33(5):1165-85
19407051
Lancet. 2009 Aug 29;374(9691):733-43
19716966
Lancet. 2007 Dec 15;370(9604):2030-43
17719083
Chest. 2006 Sep;130(3):666-71
16963660
Lancet. 2006 Mar 18;367(9514):938-40
16546542
Respiration. 2005 Sep-Oct;72(5):471-9
16210885
Lancet. 2003 Sep 27;362(9389):1053-61
14522537
Respir Med. 2003 Feb;97(2):115-22
12587960
Arthritis Rheum. 2006 Feb 15;55(1):19-26
16463407
Scand J Prim Health Care. 2001 Mar;19(1):54-7
11303549
Int J Tuberc Lung Dis. 2007 Oct;11(10):1049-61
17945060
Int J Tuberc Lung Dis. 2005 Jan;9(1):111-5
15675559
Respir Med. 2006 Feb;100(2):264-72
15975774
N Engl J Med. 2000 Jul 27;343(4):269-80
10911010
Proc Am Thorac Soc. 2006 Jul;3(5):405-8
16799082
Int J Tuberc Lung Dis. 2005 Jul;9(7):777-83
16013774
Int J Tuberc Lung Dis. 2002 Dec;6(12):1114-7
12546121
PLoS Med. 2007 Jan;4(1):e20
17227135
Int J Tuberc Lung Dis. 2004 Mar;8(3):286-98
15139466
Soc Sci Med. 2009 Jun;68(12):2240-6
19394122