The aim of this project is to develop a questionnaire that should distinguish patients with lumbar spinal stenosis (LSS) from other patients. LSS can cause significant pain and disability leading to dramatically reduced quality of life, immobility and functional limitation.

The number of people with pain and disability due to LSS is expected to increase with age due to the degenerative nature of the disease. With an aging population this could potentially become a major health economic challenge.

One of the challenges to estimate the true prevalence is the lack of a valid and reliable gold standard for LSS. To our knowledge, no diagnostic screening tool designed to estimate the prevalence of LSS in a clinical population of Danish patients with chronic low back pain (LBP) and leg pain has been developed.

The objective of this project is to develop a diagnostic screening tool for LSS - the LLS Screen. This should consist of a set of items useable in a self-administered questionnaire, a rule to compute the probability of having LSS, and a cutpoint to be used to obtain a sensitivity of 95%. The rule should be applicable in patient populations suffering from low back pain and with increased suspicion to suffer from LSS due to failure of non-surgical treatment

The specific objectives are:

A. To identify items with high content validity for diagnosing LLS B. To investigate the preliminary value of items included in the LLS screen C. To investigate the performance of the included items in the LLS screen D. To decide on the content of the final version of the LLS Screen

This project consists of four parts. Part I addresses objective A based on a literature search and qualitative semi-structured interviews. Part II addresses objective B by conducting a case-control study concurrent with a cohort study and performing a series of analyses to investigate the preliminary value and performance of the items. Part III describes the performance of the items by combining them in various ways to obtain an optimal diagnostic rule (objective C). Finally, part IV is a decision of the content of the final version of the LSS Screen based on information from Part I, II and III (objective D).

Part II:

A case-control study with cases and controls identified within a prospective clinical population based cohort study that will be boosted with cases of LSS.

Cohort design First, a prospective clinical population based cohort of patients with low back pain and/or leg pain will be initiated. Patients above 50 years of age will be included in the study at their first visit at the Spine Centre where they fill out the screening questionnaire (index test) before they are seen by a clinician. The primary diagnosis (reference test) will be assessed and determined by specialists at the Spine Centre.

Case-control design Secondly, patients with LSS will be recruited from other departments to artificially increase the prevalence of LSS. Patients with LSS will be recruited from the surgical department at the Spine Centre of Southern Denmark, Middelfart, Denmark and Department of Spine Surgery, Odense University Hospital (OUH), Odense, Denmark.

Inclusion Criteria:

• Able to read and write Danish
• Age above 50
• Low back pain and/or leg pain

Exclusion Criteria:

• None

Case/control design:

90-100 cases will be collected at surgical departments from patients assigned to surgery due to clinical symptoms of lumbar spinal stenosis

Cohort design:

Patients reffered from primary care to a publicly-funded outpatient secondary care spine clinic with primary compain of low back pain and/or leg pain