Table 4

Long term (more than 4 months) repeatability of BHR

Year and source	Participants	Age range (years)	Provocation agent and maximum concentration/cumulative dose	Time interval	Summary statistic	Within person SD (doubling doses or concentrations)	Between person SD (doubling doses or concentrations)	Intraclass correlation coefficient (ICC)
*Estimated from graphical information.
SD, standard deviation.
V/V unpublished results from Vlagtwedden/Vlaardingen study; published results also included.⁴
1982¹⁰	35 asthmatic	Not stated	Histamine, 16 mg/ml	10–30 months	PC₂₀-FEV₁	1.0*	1.7*	0.74*
1983³⁷	10 atopic asthmatic patients	23–41 at baseline	Histamine, 8.0 mg/ml	14–28 months	PC₂₀-FEV₁	0.5*	1.4*	0.87
1990³⁹	36 “responsive” workers	Not stated	Methacholine, 6.14 μmol	1 year	PD₂₀-FEV₁			0.28
1993⁴	1413 asymptomatic population sample	15–54 at baseline	Histamine, 32 mg/ml	3–22 years	PC₁₀-FEV₁			0.32
1993⁴	803 symptomatic population sample	15–54 at baseline	Histamine, 32 mg/ml	3–22 years	PC₁₀-FEV₁			0.42
V/V	2173 population sample	15–54 at baseline	Histamine, 32 mg/ml	3–22 years	PC₁₀-FEV₁	1.0	0.8	0.37
1994²⁴	27 general practice, PD₂₀⩽247 μmol on 6 occasions	18–75	Methacholine, 247 μmol	4–24 months	PD₂₀-FEV₁	1.1	1.1, calculated from ICC and within person SD	0.48
1996²⁸	10 asthmatic, PC₂₀ <9 mg/ml	25–82	Histamine, 16 mg/ml	6 months	PC₂₀-FEV₁	0.7*	1.4*	0.80*
1997³⁰	88 healthy working adults	Not stated	Methacholine, 13.06 μmol (in repeatability data)	1–3 years	PD₂₀-FEV₁	1.8	1.6	0.45