Prevalence of abnormal findings when adopting new national and international Global Lung Function Initiative reference values for spirometry in the Finnish general population

Figures & data

Table 1 Summary of measured spirometric data and predicted values by Kainu2015 (14), GLI2012 (4), and Viljanen1982 (12) in a general population sample of native Finns*

	Measured data		Mean predicted value			Measured value% predicted mean (SD)
	Mean (SD)	Range	Kainu2015	GLI2012	Viljanen1982	Kainu2015	GLI2012	Viljanen1982
FVC (L)
Male	4.89 (0.95)	2.18–8.03	5.17^§	4.90^§	5.07^§	94.1 (12.7)	99.7 (12.9)	96.2 (12.6)
Female	3.49 (0.63)	1.68–5.39	3.65^§	3.48^§	3.59^§	95.6 (11.8)	100.5 (12.3)	97.7 (12.3)
FEV1 (L)
Male	3.79 (0.86)	1.02–6.15	4.03^§	3.89^§	4.12^§	93.6 (15.5)	97.1 (15.8)	91.5 (15.2)
Female	2.78 (0.56)	0.99–4.50	2.91^§	2.82^§	2.96^§	95.6 (12.6)	98.9 (13.0)	94.3 (12.6)
FEV1/FVC (%)
Male	77.2 (8.3)	34.8–98.4	77.9^§	79.5^§	81.3^§	99.0 (10.0)	97.0 (9.9)	95.0 (10.0)
Female	79.6 (6.5)	44.7–98.6	79.4^§	81.3^§	82.4^§	100.2 (7.5)	97.9 (7.4)	96.7 (7.3)

*Males, n=597; females, n=731; ^§ p-value for paired t-test between predicted values with Viljanen1982 and Kainu 2015, Viljanen1982 and GLI2012 and Kainu2015 and GLI2012<0.001. FEV1=forced expiratory volume in one second; FVC=forced vital capacity; GLI=Global Lung Function Initiative.

Fig. 1 Difference between Kainu2015 (14) and GLI2012 (4) z-scores in a random general population sample of native Finns for (a) forced vital capacity (FVC), (b) forced expiratory volume in one second (FEV1), and (c) the FEV1/FVC ratio. Significant difference limits of ±0.3 SD as proposed by Quanjer et al. (24) are shown as dashed horizontal lines.

Table 2 Prevalence of obstruction (FEV1/FVC<LLN) and possible restrictive pattern (FVC<LLN) with both 2.5th and 5th percentile limits for Kainu2015 (14) and GLI2012 (4) reference values and the established 2.5th percentile LLN for Viljanen1982 (12) stratified by sex and applicable age category

			Obstruction (FEV1/FVC<LLN)			Possible restrictive pattern (FVC<LLN)			Decreased ventilatory capacity (FEV1<LLN)
Reference value	LLN	Age category	Male (%)	Female (%)	All (%)	Male (%)	Female (%)	All (%)	Male (%)	Female (%)	All (%)
Kainu2015	2.5%	All	7.4*	4.2*	5.6*	5.2*	3.4*	4.2*	8.0*	5.7*	6.8*
		21–65 years	5.9*^§	4.1*^§	4.9*^§	4.3*^§	2.9*^§	3.5*^§	6.6*^§	5.0*^§	5.7*^§
	5.0%	All	9.7*	7.3*	8.4*	9.4*	7.1*	8.1*	12.6*	8.9*	10.5*
		21–65 years	8.2*	7.5*	7.8*	7.8*	5.6*	6.6*	10.5*	8.1*	9.2*
GLI2012	2.5%	All	6.0*	2.3*	4.0*	3.2*	1.0*	2.0*	5.5*	2.7*	4.0*
		21–65 years	5.3*^†	2.1*^†	3.5*^†	2.7*^†	0.8*^†	1.6*^†	4.5*^†	2.7*^†	3.5*^†
	5.0%	All	9.0*	4.5*	6.6*	5.0*	3.4*	4.1*	9.0*	5.6*	7.2*
		21–65 years	7.8*	4.4*	5.9*	4.1*	3.1*	3.5*	7.4*	5.2*	6.2*
Viljanen1982	2.5%	21–65 years	11.5^§†	10.2^§†	10.8^§†	7.6^§†	6.3^§†	6.9^§†	13.9^§†	9.2^§†	11.2^§†

*Kainu2015 versus GLI2012 p<0.001; ^§Kainu2015 versus Viljanen1982 p<0.001; ^†GLI2012 versus Viljanen1982 p<0.001. LLN=lower limit of normal. The Viljanen1982 reference values provide predictions for adults 18–65 years of age (12). Males, n=597; females, n=731; in the age category 21–65 years: males n=512, females n=655; 2.5%=2.5th percentile; 5.0%=5th percentile. For the Kainu2015 and GLI2012 reference values the LLN for 2.5th percentile is z-score <−2 and the LLN for 5th percentile is z-score <−1.645. For the Viljanen1982 reference values the 2.5th percentile is defined as FEV1/FVC<88% predicted, FVC<80% predicted, and FEV1<80% predicted.

Fig. 2 Prevalence of reduced FVC (a and b), FEV1 (c and d), and FEV1/FVC ratio (e and f) in different age categories stratified by sex using the GLI2012 (4), Kainu2015 (14), and Viljanen1982 (12) reference values. For the GLI2012 and Kainu2015 reference values, the 2.5th percentile limit of z-score <−2 and 5th percentile limit of z-score <−1.645 are shown. For the Viljanen1982 reference values, the lower limit of normal (LLN) was defined as 2.5th percentile. The Viljanen1982 reference equations apply for adults 18–65 years of age, but are currently used in clinical practice also for the elderly. Extrapolated values are indicated with the black dashed line.

Fig. 3 Prevalence of degrees of reduction in FEV1 in the general population using the GLI2012 (4), Kainu2015 (14), and Viljanen1982 (12) reference values. Reductions in the GLI2012 and Kainu2015 reference values graded according to Quanjer et al. (23). Reductions in the Viljanen reference values graded according to Halttunen and Sovijärvi (22).

Table 3 Levels of agreement for obstruction (FEV1/FVC<LLN), possible restrictive pattern (FVC<LLN), and decreased ventilatory capacity (FEV1<LLN) comparing each of the three reference equations with each other

		Kappa statistic for agreement
		FEV1/FVC<LLN			FVC<LLN			FEV1<LLN
	LLN (%)	Male	Female	All	Male	Female	All	Male	Female	All
Kainu2015 (14) vs. GLI2012 (4)	5	0.94	0.75	0.86	0.68	0.63	0.66	0.82	0.76	0.79
Kainu2015 (14) vs. GLI2012 (4)	2.5	0.89	0.70	0.82	0.75	0.43	0.62	0.80	0.63	0.73
Viljanen1982 (12) vs. GLI2012 (4)	2.5	0.53	0.32	0.44	0.48	0.24	0.38	0.43	0.41	0.43
Kainu2015 (14) vs. Viljanen1982 (12)	2.5	0.61	0.52	0.57	0.69	0.58	0.64	0.59	0.72	0.65

Kainu A, Timonen KL, Toikka J, Qaiser B, Pitkäniemi J, Kotaniemi JT, etal. Reference values of spirometry for Finnish adults. Clin Physiol Funct Imaging. 2015. doi: http://dx.doi.org/10.1111/cpf.12237 [Epub ahead of print]..

 Google Scholar

Quanjer PH, Stanojevic S, Cole TJ, Baur X, Hall GL, Culver BH, etal. ERS Task Force. Multi-ethnic reference values for spirometry for the 3–95-yr age range: the global lung function 2012 equations. Eur Respir J. 2012; 40: 1324–43.

 PubMed Web of Science ®Google Scholar

Viljanen AA, Halttunen PK, Kreus K-E, Viljanen BC. Spirometric studies in non-smoking, healthy adults. Scand J Clin Lab Invest. 1982; 42(Suppl. 159): 5–20.

 Google Scholar

Quanjer PH, Stocks J, Cole TJ, Hall GL, Stanojevic S, on behalf of the Global Lungs Initiative . Influence of secular trends and sample size on reference equations for lung function tests. Eur Respir J. 2011; 37: 658–64.

 PubMed Web of Science ®Google Scholar

Quanjer PH, Pretto JJ, Drazzale DJ, Boros PW. Grading the severity of airways obstruction: new wine in new bottles. Eur Respir J. 2014; 43: 505–12.

 PubMed Web of Science ®Google Scholar

Halttunen P, Sovijärvi ARA. Use of reference values of lung function studies in the assessment of results. Suom Lääk l. 1984; 39: 2119–24. in Finnish.

 Google Scholar