Table 2.

Univariate associations between K_L factors stratified on fiber type and different characteristics of exposure assessment.

Inclusion	No. of studies	I2 (%)	Meta-KL × 100 (95% CI)	p-Valuea	AIC	Studies includedb
All studies		19		64.1		0.13 (0.04, 0.22)		–		28.2		1–19
All but Gustavsson et al. 2002		18		62.7		0.13 (0.04, 0.22)		–		18.0		1–18
Fiber
Chrysotilec		5		79.8		0.04 (–0.05, 0.12)				28.6		1–5
Amphiboles (crocidolite, amosite, tremolite)		4		45.5		0.33 (0.09, 0.56)		0.06d				6–9
Mixed		10		26.4		0.13 (0.03, 0.23)						10–19
Amphiboles and mixed		14		38.7		0.18 (0.07, 0.29)		0.10e		28.7		6–19
Documentation
Insufficientc		8		62.7		0.11 (–0.04, 0.26)		0.46		30.6		2, 3, 6, 7, 10, 11, 14, 16
Sufficient		11		67.4		0.18 (0.04, 0.33)						1, 4, 5, 8, 9, 12, 13, 15, 17–19
CE ratio (highest:lowest exposure category)
≤ 50c		9		43.7		0.10 (–0.05, 0.26)		0.38		30.3		2, 3, 8, 11, 13, 15, 16, 17, 18
> 50		10		73.7		0.20 (0.04, 0.35)						1, 4, 5, 6, 7, 9, 10, 12, 14, 19
Conversion factor (million particles per cubic foot to fiber-years/mL)
External or never PCMc		6		73.4		0.12 (–0.07, 0.30)		0.69		30.8		3, 7, 11, 15, 16, 17
Internal or always PCM		13		59.9		0.16 (0.03, 0.28)						1, 2, 4, 5, 6, 8–10, 12–14, 18, 19
Coverage of exposure data
≤ 30%c		12		57.7		0.08 (–0.01, 0.18)		0.08		27.6		1, 2, 3, 6, 7, 8, 10, 13, 14, 15, 16, 19
> 30%		7		63.3		0.27 (0.08, 0.46)						4, 5, 9, 11, 12, 17, 18
Job histories
Insufficientc		6		26.8		0.03 (–0.10, 0.17)		0.08		27.9		1, 3, 5, 11, 12, 13
Sufficient		13		64.4		0.19 (0.08, 0.30)						2, 4, 6, 7, 8, 9, 10, 14–19
aDifference between subgroups (F-test). bStudy numbers are given in Table 1. cReference category in meta-regression analyses. dTest for difference between meta-KL values for chrysotile, amphiboles, and mixed strata. eTest for difference between meta-KL values for chrysotile versus the amphiboles and mixed strata.