Comparison of covariate adjustment methods using space-time scan statistics for food animal syndromic surveillance

Table 2 Results of the space-time scan statistic using pneumonic lung condemnation data

Date of cluster	No. of abattoirs in cluster	Latitude (°N)	Longitude (°W)	Radius (Km)	No. of cases	Relative risk¹	P-value
a) Unadjusted Poisson space-time scan test
Jan 2001 - Jun 2004	5	43.94	79.69	26.60	14896	4.98	< 0.001
Jun 2004 - Nov 2007	63	49.75	92.96	1149.60	54	0.01	< 0.001
b) Animal-adjusted Poisson space-time scan test
Jan 2001 - Jun 2004	5	43.96	79.69	26.60	14896	3.12	< 0.001
Mar 2004 - Aug 2007	21	43.01	79.97	49.09	61	0.01	< 0.001
Oct 2001 - Mar 2005	1	42.98	80.60	0	4466	5.14	< 0.001
c) Model-adjusted space-time scan test
Mar 2004 - Aug 2007	16	43.01	79.97	36.88	60	0.07	< 0.001
Jan 2001 - Mar 2003	1	43.91	79.82	0	1558	0.44	< 0.001
Jan 2001- Mar 2002	4	43.30	79.90	19.98	477	6.06	< 0.001
Apr 2005 - Nov 2007	4	43.96	79.19	20.93	273	0.26	< 0.001
d) Space-time permutation scan test
Jan 2001 - Feb 2003	11	44.14	79.94	28.20	1520	0.31	< 0.001
Jan 2001 - Feb 2003	32	42.95	79.10	121.36	10514	1.55	< 0.001
Feb 2005 - Dec 2007	10	43.96	79.19	38.19	363	0.20	< 0.001
e) Space-time scan test of residuals
Jan 2001 - Mar 2003	1	43.91	79.82	0	110	---	< 0.001
Jan 2001 – Feb 2003	8	43.17	79.73	26.91	370	---	< 0.001
Jul 2003 - Jun 2004	6	43.65	79.86	29.33	109	---	< 0.001
Jan 2001 - Mar 2003	36	43.99	80.67	68.49	2280	---	< 0.001

¹The values in this column for the space-time permutation model refer to the observed/expected value.

ISSN: 1746-6148