Table 1.

Basic characteristics of 262 patients in the Swedish National Patient Register included in the review

No. of reviewed patients	262
No. females/males (%)	119 (45)/143 (55)
Mean age (range) at first validated procedure code	38 (14–74)
No. of hospitals included	27
Mean patient chart coverage (years)	5.4
No. of patients with surgical procedures validated	53
No. of separate surgical occasions validated	103
No. of surgical procedure codes validated	155
Mean no. of surgical procedure codes (SD) per hospital	6.1 (13.2)
Mean no. of surgical procedure codes (SD) per patient	3.1 (4.5)
Mean no. of surgical sessions (SD) per patient	1.9 (2.6)

NPR National patient register, SD Standard deviation