Airway reactivity to mannitol is similarly increased in chronic cigarette and water pipe smokers

Figures & data

Table 1 Demographic and clinical baseline data according to smoking status

Variables	All (n=74)	Water pipe (acute) (n=15)	Water pipe (chronic) (n=9)	Cigarette smokers (n=18)	Never-smokers (n=32)	p-value
Gender
Female, n (%)	36 (49)	8 (53)	4 (44)	8 (44)	16 (50)	0.34
Age, years	22.5 (±2.5)	21.8 (±1.5)	22.7 (±4.3)	23.0 (±2.7)	22.5 (±2.5)	0.52
Smoking
Pack-years	1.7 (0–3)	0		5.9 (4–6.5)	0	–
Cigarettes/day* (IQR)	20 (15–20)	0	0	20 (15–20)	0	–
CO, ppb	5.4 (±7.3)	2.13 (±1.8)	4.9 (±3.3)	15.3 (±8.2)	1.3 (±2.3)	<0.01
Atopic status
Allergies, n (%)	19 (26)	5 (33)	3 (33)	5 (26)	6 (19)	0.61
Prick test (positive)	38 (51)	6 (40)	5 (55)	6 (31)	13 (41)	<0.01
History of asthma, n (%)	4 (5)	1 (7)	0 (0)	0 (0)	3 (9)
Comorbidities, n (%)	4 (5)	1 (7)	0 (0)	0 (0)	3 (9)	–
Medication, n (%)	23 (31)	7 (46)	2 (22)	7 (37)	7 (22)	–
Spirometric indices
FEV1 (L)	3.8 (±0.7)	3.7 (±0.8)	3.9 (±0.8)	3.8 (±0.6)	3.7 (±0.7)	0.48
FEV1 (% predicted)	90.1 (±8.6)	91.4 (±8.6)	93.5 (±13.2)	89.0 (±3.8)	88.8 (±8.6)	0.65
FVC % (L)	4.6 (±0.8)	4.4 (±0.9)	4.8 (±1.0)	4.5 (±0.6)	4.6 (±0.7)	0.54
FVC (% predicted)	92.1 (±8.9)	91.9 (±7.3)	98.3 (±10.6)	91.2 (±7.0)	90.8 (±10.1)	0.08
FEV1/FVC* (±IQR)	0.83 (±0.1)	0.86 (±0.1)	0.81 (±0.1)	0.84 (±0.6)	0.81 (±0.1)	0.49

Notes: Data are presented as n (%), mean ± SD, or

* median (IQR). P<0.05 is significant (two-sided unpaired t-test for continuous variables, chi-square for discontinuous variables). The groups were defined as follows: 1) acute water pipe smokers (single episode of water pipe smoking, no cigarette smoking); 2) chronic water pipe smokers (weekly for ≥4 weeks; no cigarette smoking); 3) cigarette smokers (no water pipe smoking); and 4) never-smokers (no water pipe and no cigarette smoking).

Abbreviations: CO, carbon monoxide; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; IQR, interquartile range; PY, pack-years.

Figure 1 Flowchart depicting the study design.

Abbreviation: PY, pack-years.

Table 2 Mannitol challenge results in 74 subjects according to smoking status

Mannitol challenge	All (n=74)	Water pipe (acute) (n=15)	Water pipe (chronic) (n=9)	Cigarette smokers (n=18)	Never-smokers (n=32)	p-value
Positive, n (%)	7 (10)	0 (0)	0 (0)	5 (27)	2 (7)	–
Negative, n (%)	67 (90)	15 (100)	9 (100)	13 (73)	30 (93)	–
PD15 (mg),* (IQR)	–	–	–	155 (115–395)	315 (155–475)	0.04
RDR (%/mg)* (IQR)	0.011 (0.022–0.050)	0.010 (0.006–0.015)	0.013 (0.010–0.015)	0.023 (0.011–0.051)	0.007 (0.004–0.010)	0.03
Fall in % FEV1* (IQR)	−4.67 (−7.31 to −2.29)	−4.83 (−6.88 to −3.97)	−6.04 (−8.11 to −4.04)	−7.25 (−15.75 to −3.48)	−3.05 (−5.72 to −1.43)	<0.01

Notes: The groups were defined as follows: 1) acute water pipe smokers (single episode of water pipe smoking, no cigarette smoking); 2) chronic water pipe smokers (weekly for ≥4 weeks; no cigarette smoking); 3) cigarette smokers (no water pipe smoking); and 4) never-smokers (no water pipe and no cigarette smoking). Data are presented as n (%) or

* median (IQR). Response-to-dose ratio (fall in FEV₁ divided by cumulative mannitol dose given to cause this fall).

Abbreviations: FEV₁, forced expiratory volume in 1 s; IQR, interquartile range; PD₁₅, provocation dose to cause a 15% fall in FEV₁; RDR, response-to-dose ratio.