Table 2.

Undiagnosed COPD* and its overdiagnosis using postbronchodilator spirometry: cross-sectional studies of smokers (irrespective of symptoms) and other high-risk patients in primary healthcare settings

Author, year, citation	Study name location	Participant No† (%eligible‡), Sampling, selection, no/type of GP practices	Gender Age (mean (SD) years)	Prevalence of spirometry-defined COPD (%, (n/N))§	Underdiagnosis in COPD subpopulation (%, (n/N))§	Undiagnosed COPD in studied population (%, (n/N))*§	Overdiagnosis in population labelled with COPD (%, (n/N))§
Smoking per se (regardless of symptoms)
Stafyla, 201830	Thessaly, Greece	N=186 (91.2%)† Convenience; adults ≥40 years Current or ex-smokers living near 10 urban/rural practices	68% males 62.3 (13) years	17.8% (33/186)	42.4% (14/33)	7.5% (14/186)¶	NA
Casas Herrera, 2016 31	PUMA study (PLATINO) four countries South America	N=1540 (80.8%) Representative; adults ≥40 years Ever-smoker and/or biomass exposure 57 urban/rural centres	49.7% male 18.8% 40–49 33.8% 50–59 47.4% 60+ yrs	20.1% (309/1540)	77.0% (238/309)§ (range: 63%–90%)	15.5% (238/1540) § (range: 10%–23%)	30.4% (31/102)
Llordés, 201533	Spain	N=1738 (70.5%) Adults >45 years, smoking history on medical records; one primary care centre	84.3% male 59.9 (10) years	24.3% (422/1738) (95% CI 22 to 26)	56.6% (239/422)	13.8% (239/1738)¶	15.7% (34/217)
Queiroz, 201236	Brazil	N=200 (80%) Adults ≥40 years ≥20 pack-years or ≥80 hour-year biomass smoke exposure; 39 urban practices	60% male 65.9 (11) years	31.5% (63/200)	71.4% (45/63)	22.5% (45/200)¶	NA
Al Ghobain, 201138	Saudi Arabia	N=501 (36.3%) Non-consecutive; adults ≥40 years old Ever-smokers >5 years duration without prior lung disease; 60 private PC clinics	89.6% male 47.9 (6.9) years	14.2% (71/501)	**	14.2% (71/501)	NA
Hill et al42	Ontario CAN	N=1003 (15.3%) Consecutive Adults >40 years ≥20 pack-years 3 GP practices (urban/rural)	No COPD: 52.6% male, 59 (11) years; COPD: 49.5% male, 65 (9) years	20.7% (208/1003)	67.3% 138/205)¶	13.8% (138/1003)¶	43.7% (45/103)
Tinkelman, 200745	Aberdeen UK, Denver, USA	N=818 (6%–24%)‡ Representative; adults >40 years, current or past smokers, no prior OLDs, heart disease or inhaler use Query no of practices	49.3% male 58.2 (11) years	18.9% (155/818)	¶**	18.9% (155/818)	NA
Asthma-COPD registry
Melbye, 201139	DIOLUP, Norway	N=376 (21.1%) Adults ≥40 years registered with a diagnosis of asthma and/or COPD from 7 practices; latest diagnosis used	38.0% male 62 years (median)	39.6% (149/376) (COPD only)	36.2% (54/149)¶ (COPD only)	14.3% (54/376)¶ (COPD only)	25.8% (33/128)¶ (COPD only)
Medium-high COPD-risk
Dirven, 201041	Netherlands	n=147 (11.7%) undergoing spirometry† Adults 40–75 years without prior OLD at medium-to-high risk for COPD on screening survey; 1 GP at rural practices	48.7% male 55.2 (9.2) years	24.5% (37/147)††	¶**	24.5% (37/147)††	NA

*Spirometry-defined COPD based on postbronchodilator spirometry.

†COPD prevalence could be inaccurate due to insufficient sample size (online supplemental results E4), so have been omitted from the forest plots in a sensitivity analysis.

‡All % eligible figures were calculated, except when mentioned in the discussion text by Tinkelman et al.⁴⁸

§COPD was defined using the GOLD criterion, postbronchodilator forced expiratory ratio <0.70; the LLN was also reported by Casas Herrera et al³¹ (data not shown).

¶Data needed to be deduced and calculated from the figures given (by the present authors).

**Percentage undiagnosed in the COPD subpopulation was 100% as the population excluded patients with a history of COPD (3 of total of 7 studies).

††Data from the manuscript did not quite add up to the percentages given.^{31 45}

ACO, asthma-COPD overlap; BDR, bronchodilator response; COPD, chronic obstructive pulmonary disease; GOLD, Global Initiative for Chronic Obstructive Lung Disease; GP, general practitioner; LLN, lower limit of normal; LRTI, lower respiratory tract infection; NA, not available; OLDs, obstructive lung diseases; PC, primary care.