Pulmonary Function Assessment in Myasthenia Gravis Patients in a National Referral Hospital in Indonesia

Figures & data

Table 1 Characteristics of MG Patients and Healthy Controls

Characteristics	MG Patients (n = 70)	Healthy Controls (n =16)	p
Sex (n (%))			0.560
Male	21 (30)	6 (37.5)
Female	49 (70)	10 (62.5)
Age (years; mean ± SD)	47.7 ± 13.4	38.1 ± 9.0	0.007
Body height in cm (mean ± SD)	159.99 ± 7.74	161.19 ±6.79	0.569
Onset of MG (n (%))
Early onset MG (<50 years old)	48 (68.6)
Late onset MG (≥50 years old)	22 (31.4)
MG Type (n (%))
Ocular	31 (44.3%)
Generalized	39 (55.7%)
Duration of disease (years; median (range))	3 (0.25–44)
MG composite score (median (range))	3 (0–14)
Pyridostigmine (mg/day; median (range))	180 (120–300)
MGFA (n (%))
I	38 (54.3)
II	27 (38.6)
III	5 (7.1)

Abbreviations: MGFA, Myasthenia Gravis Foundation of America; MG, myasthenia gravis; SD, standard deviation.

Table 2 Comparison of Pulmonary Functional Characteristics Between MG Patients and Healthy Controls

Characteristic	MG Patients (n=70)	Healthy Controls (n=16)	p
SBCT (median (range))	28 (14–59)	52 (23–71)	0.000
PFM EU (L/min; median (range))	423 (345–626)	432 (389–629)	0.077
PFM predicted (L/min; mean ± SD)	81.4 ± 14.3	88.6 ± 12.3	0.057
FVC1 (L; mean ± SD)	2.1 ± 0.6	2.9 ± 1	0.000
FEV1 (L; mean ± SD)	1.9 ± 0.6	2.6 ± 0.96	0.001
FEV1/FVC1 ratio (%; median (range))	93 (0–100)	89.5 (78–97)	0.079

Abbreviations: SBCT, single breath counting test; PFM, peak flow meter; FVC1, forced vital capacity first second; FEV1, forced expiratory volume first second.

Table 3 Comparison of Pulmonary Functional Characteristics in Ocular and Generalized MG Patients

Characteristic	MG Ocular (n=34)	MG General (n =36)	p
SBCT (median (range))	30.0 (15.0–51.0)	25.0 (14.0–59.0)	0.175
PFM EU (L/min; median (range))	422 (345–612)	427 (355–626)	0.401
PFM predicted (L; mean ± SD)	82.9 ± 13.1	79.8 ± 15.2	0.701
FVC1 (L; mean ± SD)	2.1 ± 0.7	2.2 ± 0.6	0.279
FEV1 (L; mean ± SD)	1.9 ± 0.6	1.9 ± 0.6	0.929
FEV1/FVC1 ratio (%; median (range))	92.9 (75–100)	86.4 (0–100)	0.102

Abbreviations: SBCT, single breath counting test; PFM, peak flow meter; FVC1, forced vital capacity first second; FEV1, forced expiratory volume first second.

Table 4 Comparison of Pulmonary Functional Characteristics in MG Patients with and without Crisis

Characteristic	MG with History of MG Crisis (n=23)	MG without History of MG Crisis (n=47)	p
SBCT (mean ± SD)	25.6 ± 7.0	30.9 ± 11.1	0.124
PFM EU (L/min; median (range))	423 (355–626)	428 (345–625)	0.639
PFM predicted (L/min; median (range))	75.1 (37.5–100)	82.9 (55.5–111)	0.80
FVC1 (L; median (range))	2.0 (1.1–3.2)	2.0 (1.3–3.9)	0.413
FEV1 (L; median (range))	1.9 (0.9–2.9)	1.8 (0.0–3.4)	0.726
FEV1/FVC1 ratio (%; median (range))	93 (75–100)	93 (0–100)	0.745

Abbreviations: SBCT, single breath counting test; PFM, peak flow meter; FVC1, forced vital capacity first second; FEV1, forced expiratory volume first second.

Table 5 Association Between Spirometry with SBCT and PFM in MG Patients

Characteristic	Normal Spirometry (n=23)	Abnormal Spirometry (n=47)	p
SBCT (median (range))	27 (15–46)	28 (14–59)	0.935
PFM EU (L/min; median (range))	421 (345–593)	427 (355–626)	0.604
PFM predicted (L/min; mean ± SD)	84.5 ± 11.6	79.5 ± 15.3	0.179

Abbreviations: SBCT, single breath counting test; PFM, peak flow meter.

Table 6 Association Between PFM with SBCT, FVC1, and FEV1 in MG Patients

Characteristic	Green PFM (n=40)	Yellow–Red PFM (n=30)	p
SBCT (median (range))	30 (17–59)	24 (14–51)	0.01
FVC1 (L; mean ± SD)	2.3 ± 0.6	2.0 ± 0.5	0.045
FEV1 (L; mean ± SD)	2.0 ± 0.6	1.7 ± 0.6	0.057
FVC1/FEV1 ratio (%; median (range))	93 (0–100)	93 (17–100)	0.6

Abbreviations: SBCT, single breath counting test; FVC1, forced vital capacity first second; FEV1, forced expiratory volume first second.

Table 7 Correlation of Each Pulmonary Functional Characteristics*

Characteristic	r in Healthy Controls	r in MG Patients
Single breath counting test and FVC1	0.800*	0.440*
Single breath counting test and FEV1	0.832*	0.427*
PFM EU and FVC1	0.873*	0.711*
PFM EU and FEV1	0.922*	0.514*

Note: *All correlation analysis of pulmonary functional characteristics have P <0.05.