Table 3. Comparison of MP positivity between different laboratory tests in patients of different ages.

BALF PCR	IgM				Paired sera IgG				NPA PCR				Combined IgM and NPA PCR
	(+)	(−)	Total		(+)	(−)	Total		(+)	(−)	Total		(+)	(−)	Total
In patients ≤1-year-old
(+)	5	18	23		9	14	23		7	16	23		9	14	23
(−)	5	26	31		18	13	31		6	25	31		10	21	31
Total	10	44	54		27	27	54		13	41	54		19	35	54
Kappa		0.061				−0.185				0.117				0.07
P value		0.6				0.169				0.346				0.601
In patients 1–3 years old
(+)	17	6	23		12	11	23		15	8	23		18	5	23
(−)	11	40	51		24	27	51		4	47	51		29	25	51
Total	28	46	74		36	38	74		19	55	74		31	30	74
Kappa		0.494				0.044				0.603				0.189
P value		0				0.684				0				0.043
In patients 3–5 years old
(+)	36	16	52		30	22	52		30	22	52		41	11	52
(−)	3	22	25		17	8	25		2	23	25		3	22	25
Total	39	38	77		47	30	77		32	45	77		44	33	77
Kappa		0.504				-0.098				0.411				0.617
P value		0				0.385				0				0
In patients >5 years old
(+)	47	19	66		38	28	66		48	18	66		56	10	66
(−)	1	24	25		14	11	25		0	25	25		1	24	25
Total	48	43	91		52	39	91		48	43	91		57	34	91
Kappa		0.549				0.06				0.594				0.727
P value		0				0.542				0				0

MP, Mycoplasma pneumoniae; IgM, immunoglobulin M; IgG, immunoglobulin G; NPA, nasopharyngeal aspirate; BALF, bronchoalveolar lavage fluid; PCR, polymerase chain reaction.