Table 4.

Comparison of lung function impairment categories: Knudsen et al. equations,¹⁹ GLI 2012, GLI 2022 and the 2024 Tanzanian reference equations.^*

Impairment type and severity grading	Tanzania 2024	Knudsen et al. 2011	GLI 2012	GLI 2022
Normal	310	320	271	296
Obstruction–mild	12	14	13	9
Obstruction–moderate	0	1	4	3
Obstruction–severe	0	2	0	0
Restriction–mild	15	5	39	22
Restriction–moderate	2	1	9	6
Restriction–severe	0	0	0	0
Mixed–mild	0	0	0	0
Mixed–moderate	2	0	0	0
Mixed–severe	2	0	7	7

^*While only 23 subjects had abnormal lung function according to the Knudsen et al. 2011¹⁹ reference standard, 72 subjects had a lung impairment in spirometry if GLI 2012 and standards were used and 47 subjects if GLI 2022 standards were used. However, the 2024 Tanzanian prediction equations classified 33 participants with abnormal lung function.

GLI = Global Lung Initiative.