Table 7.

Sub-group analysis with the papers reporting lameness incidence rate (100 cow-years) at cow level after outlier removal.

Moderator	Subgroup	No of studies per subgroup	Pooled incidence rate (100 cow-years) per subgroup	95% CI	P-value for QM	Residual heterogeneity (H)	Residual heterogeneity (I2) (%)
Lameness data source	Mobility scoring system	13	36.9	24.2–52.4	0.989	62.93	100.0
	Records	16	36.8	26.9–48.4
Study Type	Observational	22	30.7	23.1–39.5	<0.001*	63.37	100.0
	Experimental	7	63.4	45.4–84.4
Study Farm(s) Location	Not at Research Institute	22	33.9	25.8–43.1	0.309	63.57	100.0
	At Research Institute	7	48.3	24.1–80.9
Breed	Holsteina	20	45.7	34.7–58.2	0.0020*	45.83	100.0
	Other	6	19.4	9.8–32.4
Grazing regime	Grazing	13	64.6	43.6–90.1	<0.001*	19.66	99.7
	Other	5	17.5	12.2–23.9
Housing System	Multiple	6	14.8	7.5–24.6	0.03*	43.14	99.9
	Cubicle	12	54.2	19.2–106.9
Calving Pattern	Year-round	5	52.4	18.2–104.2	0.577	43.14	99.9
	Other	9	39.5	22.4–61.3
Start of data collection (year) 1	1995 and onwards	19	38.1	29.8–47.5	0.694	51.55	100.0
	Before 1995	10	34.6	21.2–51.3
Start of data collection (year) 2	2000 and onwards	14	43.7	28.5–62.1	0.164	47.84	100.0
	Before 2000	15	31.0	23.3–39.8
Start of data collection (year) 3	2005 and onwards	9	55.8	28.9–91.5	0.066	45.37	100.0
	Before 2005	20	29.3	23.6–35.6
Start of data collection (year) 4	2008 and onwards	8	47.8	22.1–83.4	0.316	45.51	100.0
	Before 2008	21	32.9	26.5–40.1
Start of data collection (year) 5	2010 and onwards	6	31.6	13.7–56.8	0.583	52.07	100.0
	Before 2010	23	38.5	28.9–49.5
Sample Size a	1,230 animals or more	17	24.5	17.1–33.3	0.0019*	62.00	100.0
	less than 1,230 animals	12	60.2	38.3–86.9
Sample Size b	More than 5 farms and 1230 animals	11	20.7	14.3–28.2	0.0021*	43.29	99.9
	less than 5 farms and/or 1,230 animals	18	49.7	31.9–71.6

^aHerds which cows were mainly Holstein, Friesian and/or Holstein-Friesian.

^*Variables considered as moderators.