An Estimate of the Prevalence of COPD in Africa: A Systematic Analysis

Figures & data

Table 1.  Search terms

1	africa/ or exp africa, northern/ or exp algeria/ or exp egypt/ or exp libya/ or exp morocco/ or exp tunisia/ or exp “africa south of the sahara”/ or exp africa, central/ or exp cameroon/ or exp central african republic/ or exp chad/ or exp congo/ or exp “democratic republic of the congo”/ or exp equatorial guinea/ or exp gabon/ or exp africa, eastern/ or exp burundi/ or exp djibouti/ or exp eritrea/ or exp ethiopia/ or exp kenya/ or exp rwanda/ or exp somalia/ or exp sudan/ or exp tanzania/ or exp uganda/ or exp africa, southern/ or exp angola/ or exp botswana/ or exp lesotho/ or exp malawi/ or exp mozambique/ or exp namibia/ or exp south africa/ or exp swaziland/ or exp zambia/ or exp zimbabwe/ or exp africa, western/ or exp benin/ or exp burkina faso/ or exp cape verde/ or exp cote d'ivoire/ or exp gambia/ or exp ghana/ or exp guinea/ or exp guinea-bissau/ or exp liberia/ or exp mali/ or exp mauritania/ or exp niger/ or exp nigeria/ or exp senegal/ or exp sierra leone/ or exp togo/
2	exp vital statistics/ or exp incidence/
3	(incidence* or prevalence* or morbidity or mortality).tw.
4	(disease adj3 burden).tw.
5	exp “cost of illness”/
6	exp quality-adjusted life years/
7	QALY.tw.
8	Disability adjusted life years.mp.
9	(initial adj2 burden).tw.
10	exp risk factors/
11	2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10
12	exp Emphysema/
13	copd.mp.
14	exp bronchitis, chronic/ or exp pulmonary disease, chronic obstructive/ or exp pulmonary emphysema/
15	12 or 13 or 14
16	1 and 11 and 15

Table 2.  GOLD and ATS/ERS COPD diagnostic criteria

GOLD criteria (20)
Stage	Definition
I	FEV1/FVC < 0.7 FEV1≥ 80% predicted
II	FEV1/FVC < 0.7 FEV1 50–80% predicted
III	FEV1/FVC < 0.7 FEV1 30–50% predicted
IV	FEV1/FVC < 0.7 FEV1 < 30% predicted or FEV1 < 50% predicted plus chronic respiratory failure
ATS/ERS criteria (21)
Severity	Definition
At risk  Patients who:  –Smoke/Pollutant exposure  –Cough/Sputum/Dyspnoea  –Family history of respiratory disease	Post-bronchodilator FEV1/FVC > 0.7 FEV1 ≥ 80% predicted
Mild COPD	Post-bronchodilator FEV1/FVC ≤ 0.7 FEV1 ≥ 80% predicted
Moderate COPD	Post-bronchodilator FEV1/FVC ≤ 0.7 FEV1 50–80% predicted
Severe COPD	Post-bronchodilator FEV1/FVC ≤ 0.7 FEV1 30–50% predicted
Very Severe COPD	Post-bronchodilator FEV1/FVC ≤ 0.7 FEV1 < 30% predicted

ATS: American Thoracic Society, ERS: European Respiratory Society, FEV₁: forced expiratory volume in one second, FVC: forced vital capacity, GOLD: Global Initiative for chronic Obstructive Lung Disease.

Figure 1.  Flow chart of the study selection.

Table 3.  Overall study characteristics

Author	Country, Location	Study setting	Study period	Age range/Mean age	Case definition
Ayo-Yusuf et al. (33)	South Africa, National DHS	Mixed	1998	≥25 years	BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Buist, A.S. et al. (23)	South Africa, Cape town	Mixed	2004–2006	≥40 years	GOLD criteria: postbronchodilator FEV1/FVC < 0.7
Desalu OO (24)	Nigeria, Ekiti State	Rural	2009	≥35 years (mean age 55.5 ± 10.2)	BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Desalu et al. (25)	Nigeria, Ijero-Ekiti	Rural	2009	55 ± 10 years	ECRHS & BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Ehrlich, R.I. et al. (26)	South Africa, National Household Survey	Mixed	2004	≥15 years	BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Fullerton, D.J. et al. (27)	Malawi, Blantyre and Chikwawa districts	Mixed Urban and Rural	2001	≥30 years (mean age 45.0 years)	ATS/ERS criteria: FEV1/FVC < 0.7
Gathuru, I.M. et al. (28)	Nigeria, Benin	Urban	1992–1999	30–69 yrs (mean age 48.8 years)	ATS/ERS criteria: FEV1/FVC < 0.7; BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Girdler-Brown et al. (31)	South Africa, Basotho	Occupational	2007–2008	Mean age 49.4 years	ATS/ERS criteria: FEV1/FVC < 0.7; BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Khelafi, R. et al. (29)	Algeria, Algiers	Mixed	2009	21–89 years	GOLD criteria: postbronchodilator FEV1/FVC < 0.7
Laraqui Hosni et al. (32)	Morocco, Rabat	Occupational	2001–2002	≥15 years	BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Mengesha & Bekele (34)	Ethiopia, Addis Ababa	Occupational	1997–1998	37 ± 8.0 years	BMRC (1965) & ATS (1962) criteria: productive cough for >3 months/year for at least 2 successive years
Musafiri, S. et al. (30)	Rwanda, Kigali	Mixed	2008–2009	≥15 years (mean age 38.3 years)	ATS/ERS guidelines: FEV1/FVC < LLN. LLN = lower limit of normal, which is 5th percentile (1.645 SD below predicted); BMRC criteria: cough with phlegm every day for at least 3 months a year for at least 2 successive years
Tabka et al. (35)	Tunisia, Tunis	Occupational	1998	≥15 years	BMRC criteria: productive cough for >3 months/year for at least 2 successive years

ATS: American Thoracic Society, BMRC: British Medical Research Council, DHS: Demographic and Health Survey, ECRHS: European Community Respiratory Health Survey, ERS: European Respiratory Society, FEV1: Forced Expiratory Volume in 1 second, FVC: Forced Vital Capacity, GOLD: Global Initiative for chronic Obstructive Lung Disease, LLN: lower limit of normal.

Table 4.  Distribution of studies

Country	Number of studies
Algeria (29)	1
Ethiopia (34)	1
Malawi (27)	1
Morocco (32)	1
Nigeria (24, 25, 28)	3
Rwanda (30)	1
South Africa (23, 26, 31, 33)	4
Tunisia (35)	1
Study type
Spirometric (23, 27–29, 31)	5
Non-spirometric (24–26, 28, 30–35)	10
Studies reporting both (28, 31)	2
Study setting
Rural (24, 25)	2
Urban (28)	1
Mixed (23, 26, 27, 29, 30, 33)	6
Occupational (31, 32, 34, 35)	4
Study duration
<1 year (24–27, 29, 33, 35)	7
1–3 years (23, 30–32, 34)	5
>3 years (28)	2
Sample size
<1000 (23–25, 27, 28, 31, 32, 34, 35)	9
1001–3000 (29, 30)	2
>3000 (26, 33)	2

Figure 2.  Boxplots of the prevalence of COPD for the studies based on spirometry and all other studies.

Table 5.  Statistics for year, mean age, number of cases, sample size and prevalence of COPD for the spirometry-based studies and all other studies

Spirometry-based studies
Statistics		Year	Mean age	No. of cases	Sample size	% prevalence of COPD
Data points		13	13	13	13	13
Mean		2004.85	55.2462	55.57	389.85	15.5946
Median		2006.00	53.5000	45.00	290.00	13.4000
Std. Deviation		3.934	11.49461	50.329	285.518	7.91887
Range		10	39.50	191	896	24.15
Percentiles	25	2000.00	46.9000	20.11	160.00	9.3700
	75	2008.50	62.0000	77.84	633.00	22.0500
Other studies
Statistics		Year	Mean age	No. of cases	Sample size	% prevalence of COPD
Data points		20	20	20	20	20
Mean		2004.65	49.1750	68.52	1797.10	7.0015
Median		2004.00	49.1000	55.50	516.00	4.0350
Std. Deviation		4.043	14.29497	84.273	3044.636	7.18240
Range		11	60.00	358	13411	23.80
Percentiles	25	2002.50	39.5000	6.81	116.75	2.1225
	75	2009.00	58.5000	80.00	2260.50	8.8500

Figure 3.  Plot of the prevalence of COPD versus the mean age from the spirometry-based studies.

Table 6.  Prevalence of COPD in terms of smoking from selected studies

Author	Study setting	Sample size	COPD prevalence (%)	Current smokers (%)	Odds ratio of COPD among current smokers (95% CI)
Ayo-Yusuf et al. (33)	Mixed	4464	3.2	7.3	2.84 (1.60, 5.04)^†
Buist, A.S. et al. (23)	Mixed	847	23.8	30.0*	1.15 (1.00, 1.32)**
Desalu OO (24)	Rural	391	5.6	2.6	6.37 (2.12, 19.4)
Ehrlich, R.I. et al. (26)	Mixed	13468	2.6	21.7	–
Gathuru, I.M. et al. (28)	Urban	270	9.5	10.8	–
Musafiri, S. et al. (30)	Mixed	1824	4.5	16.7	3.22 (1.53, 4.31)

^†Odds ratio in women, *20 pack-years, **10 pack-years.