P. Endler, P. Ekman, F. Hellström, H. Möller, P. Gerdhem

February 2020, Volume 29, Issue 2, pp 213 - 220 Original Article Read Full Article 10.1007/s00586-019-06181-0

First Online: 28 November 2019

Background and purpose

Loss to follow-up in observational studies may skew results and hamper study reliability. We evaluated the importance of loss to follow-up in the Swedish spine register.


Patients operated in the lumbar spine and scheduled for a postal questionnaire follow-up during part of 2016 were identified. Out of the 351 patients, 203 had responded. After multiple attempts, 115 of the 148 non-responders were reached; 68 returned the complete questionnaire; and 47 answered a brief questionnaire by phone. Analyses were made with the Chi-square test, analysis of covariance or logistic regression. Some analyses were adjusted.


At baseline, the non-responders were younger than the responders (55 vs 61 years, p 


After surgery for lumbar spine degenerative disorders, non-responders achieve similar outcome as responders in the Swedish spine register, with the exception of a lower mental health and less perceived improvement in back pain.

Graphic abstract

These slides can be retrieved under Electronic Supplementary Material. [graphic not available: see fulltext]

Read Full Article