Background and aims. There are no previous studies of spinal surgery rates in Norway. The purpose of this study was to investigate trends in lumbar spine surgery in Norway over 15 years, including length of hospital stay, and rates of complications and reoperations.
Methods. Hospital patient administrative data was linked with sociodemographic data from the National Registry in Norway. Annual rates of simple (microsurgical discectomy, decompression) and complex surgical procedures (fusion, disc prosthesis) in the lumbar spine were analyzed in all patients aged ≥ 18 years discharged from Norwegian public hospitals between 1999 and 2013. 
Results. The rate of lumbar spine surgery increased by 54%, from 78 (95%CI [75-80]) to 120 [107-113] per 100,000, from 1999 to 2013. More men had simple surgery whereas more women had complex surgery. Among elderly people over 75 years, lumbar surgery increased by a factor of 4.5 during the 15-year period. The rates of complications were low, but increased from 0.9 in 1999 to 2.3 per 1000 in 2013. 
Conclusions. There was an increase in spinal surgery in Norway, similar to trends in other Western world countries. The rise in lumbar surgery among elderly people represents a challenge for health services, given our ageing population.

05 - TRENDS IN LUMBAR SPINE SURGERY IN NORWAY: A 15-YEAR STUDY