Aim: The aim of this study was to evaluate the patterns of compliance and the frequency of adenomas and neoplasms in a Swedish population.
Methods: In 1996, 2000 men and women born in 1935 or 1936 were selected at random from the population registers of Uppsala and Malmö/Lund. All subjects were invited by mail to participate. In a randomised study design, subjects were either called up by a nurse to schedule the appointment for sigmoidoscopy or instructed to call themselves. At sigmoidoscopy subjects with a cancer, an adenoma (neoplastic polyp) or more than three hyperplastic polyps were scheduled for a complete colonoscopy.
Results: Thirty-nine percent (770/1988) of all the invited subjects had a sigmoidoscopy. The participation differed between the two centres, 47% at the Uppsala centre and 30% at the Malmö/Lund centre (P<0.01). There was no statistically significant difference between the two different invitation groups. In all, 98 subjects (13%) were planned for colonoscopy. Thirty-one (35%) of the subjects having a colonoscopy were women and 57 (65%) were men. Fifty-five true adenomas were found in 46 subjects. All together, six subjects had proximal adenomas. Five adenocarcinomas were diagnosed, all within the reach of the sigmoidoscope.
Conclusions: The compliance was lower and the adenomas were fewer than expected. To increase compliance it is necessary with rigorously controlled invitation routines.