Montgomery F, Willner S
Department of Orthopaedics, University Hospital of Malmö, Sweden.
Spine (Phila Pa 1976). 1997 Apr 1;22(7):772-4. doi: 10.1097/00007632-199704010-00012.
This study analyzed the incidence of treatment of scoliosis using a cross-sectional and a longitudinal technique.
To follow the incidence of treated scoliosis in Malmö, Sweden, in children born between 1970 and 1977 and compare observations with those of a study from 1988, in which the incidence of this disorder was followed in children born between 1963 to 1969.
During the late 1970s and early 1980s, the incidence of treated scoliosis decreased yearly in Malmö. This trend was supported by other reports. However, introduction of worldwide screening for scoliosis was a confounding factor. When cohorts of children born between 1963 and 1969 were analyzed, no change was found. In a study in Malmö in 1988, this was shown to be an effect of using a longitudinal instead of a cross-sectional technique of analyzing the data.
In a cross-sectional study, the authors registered all new treatments for idiopathic scoliosis, brace treatments, or direct surgery, for each year between 1984 and 1993. In a longitudinal study, all new treatments in each cohort of children born between 1970 and 1977 were followed. The results were compared with figures from the 1988 study.
After the introduction of school screening in 1976, a peak in the incidence of treated scoliosis was seen in 1977. After a continuous decrease in the incidence until 1983, a steady state developed. In cohorts born between 1963 and 1977, the incidence is neither increasing nor decreasing.
In cohorts of children followed in a longitudinal study over a 15-year period (born between 1963 and 1977), there is no support for a change in the natural history of idiopathic scoliosis.
