Table 3 Equations proposed for the conversion of the assessments A into scores S for the five components of the BASMI_lin

	S = 0 if:	Between 0 and 10:	S = 10 if:
Lateral lumbar flexion* (cm)	A⩾21.1	S = (21.1−A)/2.1	A⩽0.1
Tragus-to-wall distance* (cm)	A⩽8	S = (A−8)/3	A⩾38
Lumbar flexion (modified Schober) (cm)	A⩾7.4	S = (7.4−A)/0.7	A⩽0.4
Intermalleolar distance (cm)	A⩾124.5	S = (124.5−A)/10	A⩽24.5
Cervical rotation angle* (°)	A⩾89.3	S = (89.3−A)/8.5	A⩽4.3

*For lateral lumbar flexion, tragus-to-wall distance, and cervical rotation the average of right and left should be taken.
If a score lies beyond the range 0–10, the values 0 or 10 have to be used, respectively. For facilitating computer calculations with “if... then... else” fields in a table calculation program such as Microsoft Excel, the limits of the linear ranges are also given. The BASMI_lin is the mean of the five scores.
BASMI, Bath Ankylosing Spondylitis Metrology Index.