Similarly with our study, Grotle and colleagues also analysed figures from the Norwegian Patient Registry and found that the treatment rate for lumbar spine surgery in Norway increased from 78 to 120 procedures per 100 000 inhabitants per year from 1999 to 2013 (10). We found that the rate has remained consistently at the same level in the following years. However, the number of procedures nevertheless increased by nearly 500 from 2014 to 2018. The studies indicate that this trend is mainly caused by demographic change in the form of an increasing population and a growing proportion of older people. The increasing population and the growing proportion of older people will help generate a continued increase in the number of procedures per year, especially for lumbar stenosis that affects the elderly, even if the rates remain stable.
The treatment rate remained stable also for those who were resident in the area of Northern Norway Regional Health Authority, but at a lower level (91 %) than the national average. Similar differences between the regions were observed also in the period 1999–2013 (M. Grotle, personal communication). The large annual variations in some districts of residence are likely to be random in areas with few inhabitants. The differences in average rates were small, with the exception of residents in the Bodø district, who had a rate of 72 % of the national average in the period 2015–2018. This is equivalent to 20 procedures less than the national average per year.
The treatment rates in Norway are far lower than those for equivalent spine surgery in the United States, where 149 simple and 144 complex procedures were undertaken per 100 000 inhabitants in 2012 (4). In the UK, the rate for all lumbar spine procedures amounted to 49 per 100 000 inhabitants in 2013, while in Ireland, the rate remained stable at approximately 26 per 100 000 inhabitants per year in the period 2012–2016 (9, 15). The British study did not state whether procedures undertaken in private hospitals were included, while the Irish study only analysed data from public hospitals. It is nevertheless likely that these rates are lower than in Norway.
The Norwegian Patient Registry does not include surgical procedures that have been undertaken in private hospitals and that have been paid for by the patients themselves or by private health insurance. However, these hospitals report data to the National Quality Registry for Spine Surgery, which in 2018 recorded 862 procedures undertaken by seven private hospitals. More than 10 % of all spine surgery procedures are undertaken without any public funding. The total Norwegian treatment rate may thus be close to 140 procedures per 100 000 inhabitants per year. Patients who undergo surgery in private hospitals in Norway are on average younger and have a higher level of education, better health and fewer risk factors for an adverse outcome when compared to patients in public hospitals (16). Private health insurance most likely contributes to geographical variation and less equality in service provision.