Recently there has been some controversy as the National Institute for Clinical Excellence in the UK have stopped recommending acupuncture for back pain. The reasons are complex after review of clinical research. However, it seems that there were serious flaws in the design of the most recent NICE study, and Mel Koppleman has come up with a detailed analysis of the processes used by NICE to amend their guidelines which removed acupuncture as recommended treatment for lower back pain.
For more on this please see:
http://www.abetterwaytohealth.com/the-nice-low-back-pain-guidelines-a-big-misunderstanding/
For practical purposes Acupuncture still works very well for Low back pain (of course, even better if osteopathy and manipulation can be added as tools in the toolbox). It seems that NICE in the UK have reviewed current research and for complex reasons removed their recommendation of acupuncture for low back pain. This decision is controversial and complex - and Mike Cummings (an academic and medical acupuncturist) has reviewed and responded to this.
Large studies work generically with large populations and statistical number-crunching. There's nothing wrong with this, and indeed Evidenced -based medicine puts every medical intervention, procedure and treatment protocol under scrutiny, as it should.
For examples of this, please see:
http://www.christchurch-osteopathy-acupuncture.co.nz/acupuncture/effectiveness.html
But just remember that we treat 'people' not 'populations', 'individuals' not 'diseases'. This is far more relevant for individual clinicians, be they GPs, acupuncturists, chiropractors, physiotherapists or osteopaths.
Know your patient. Get it right. Do good work - and use safe effective interventions. Acupuncture is definitely one of them. It has stood the test of time (several thousands of years) and modern research will no doubt give differing indications, and probably come round again. It usually does.
Have a look at:
http://www.christchurch-osteopathy-acupuncture.co.nz/acupuncture/scientificBasis.html
Your patients know it works, for them. They keep coming back, and tell their friends (and their GPs). Good enough.