Is chiropractic treatment safe, effective and cost-effective for back pain?

In general yes: In general, yes, although there are some contradictory studies out there. The only times i would advise against chiropractic treatment are if there is documented spinal instability, or a fracture or other significant intravertebral pathology, or significant nerve or spinal cord compression/impingement.

Inconclusive: There isn't enough evidence to draw sound conclusions on the effectiveness or cost-effectiveness of chiropractic adjustments for back pain, however, there is quite a bit of anecdotal evidence. I would caution that chiropractic adjustments of the neck have been known to cause vertebral artery dissections, which can lead to debilitating strokes and/or death. I would strongly advise against this.