PBR is a big topic with the healthcare fields in the US. Two federal agencies have programs devoted to exploring the topic: the Agency for Healthcare Research and Quality (AHRQ) and the National Health Institutes (NIH).
The AHRQ has a directory listing of PBRNs, tracking their purposes and progress. There is also an extensive reading room there describing initiatives and findings. Go to www.ahrq.gov and search on PBR for quite a long list.

The NIH has been instrumental in the formation of a National Dental Practice-Based Research Network. The program was funded beginning in 2005 and has a number of publications and findings.

Another great source of reading material is the national library of medicine, accessed through PubMed. The most general search of PubMed for the term ‘practice-based research’ produces more than 2200 hits. Many of these citations can be downloaded for free if they are in the PubMed Central database. Combine the above search with the term ‘Chiropractic’ and you get 30 citations.