Low back pain: Time to get off the treadmill

Nonspecific low back pain (large circle) may consist of a number of largely unidentified subentities (smaller circles LBP1, LBP2, etc), each having its own set of causal mechanisms (C1, C2, etc).

Sampling method in one study may result in a disproportionately large number of people from one or several specific subentities of LBP.

Sampling method in another study may result in a disproportionately large number of people from some other specific subentities of LBP