Psychiatric comorbidity as predictor of costs in back pain patients undergoing disc surgery: a longitudinal observational study

Table 1 Missing values of resource utilization

	T0		T1		T2
	N	Max % missings	N	Max % missings	N	Max % missings
Hospital fee data for DRG calculation of index treatment	531	21.09	-	-	-	-
Other hospital related variables	531	0.19	484	0.41	284	0
Rehabilitation related variables	-	-	484	0.21	284	0
Outpatient physician visits	531	0	484	0.41	284	0.70
Outpatient non-physician visits	531	0.19	484	0.62	284	1.06
Number of drug units consumed	1,455^a	2.27	635^a	9.61	588^a	6.97
Medical goods consumed	531	0	484	0	284	1.06
Informal care related variables	531	0.75	484	2.69	284	0.35
Transports related variables	531	0.56	484	2.48	284	1.76
Loss of productivity related variables	427^b	2.34	357^b	2.80	203^b	2.46

^a number and percentage refer to the overall number of drug labels reported; ^b percentage refers to the number of employed.

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