BMC Public Health 2009, 9:101 http://www.biomedcentral.com/1471-2458/9/101 a regression to the mean [22]. However, our study sample was not primarily composed of very heavy drinkers, and we also observed improvements in readiness, importance and confidence regarding changing drinking, which were in the opposite direction than any hypothesized regres- sion to the mean, given the relatively high levels of readi- ness, importance and confidence in the study population at baseline. Assessment effects (improvements due to being asked questions about drinking and discussing answers to those questions) have also been suggested as causes of improvements in drinking [45,46]. This expo- sure may have in part accounted for improvements in our sample. But if asking about alcohol and discussing drink- ing in primary care are in fact responsible for improve- ments, such effects should be viewed as favorable exposures in the primary care setting, and as part of the course in these patients, rather than as methodological nuisances. This study has some strengths. To our knowledge, this is the first study to explore changes in readiness, importance and confidence during a single primary care visit. We described rapid changes in these constructs. We were also able to describe changes in readiness, importance or con- fidence and drinking over a 6 month period. Subjects studied were participants in a trial but there was no exper- imental brief counseling intervention nor a significant treatment effect on drinking amounts. The study also has some limitations. First, the applicabil- ity of our findings may be limited to primary care patients with unhealthy alcohol use who agree to be screened and followed in a research study, and to those with similar characteristics as in our sample (e.g. 32% reporting no alcohol problems, a third with illicit drug use). Although participants differed little from those who did not partici- pate, participants did drink more. Similarly, subjects lost to the analytic sample differed little from those studied except on gender. The effects of these differences can be considered in the interpretation of our results. Second, findings are from secondary data analyses. Causality (of predictors) cannot be inferred, and there could be many explanations for changes in the readiness constructs. However, observational studies such as this one are likely among the best ways to study the natural course of behav- ior change constructs and changes in drinking, particu- larly prospective studies. Third, in our attempt to explore changes over time, we had to combine actual behavior (changes in alcohol consumption) with cognitions about behavior change. It is likely that these two dimensions reflect different aspects of behavior. We presented data on the dimensions separately (and combined) but per- formed regression analyses on the combined outcome. From a clinical perspective, improvements in either drink- ing or readiness (combined) seem to be most relevant. Also, the interpretation of a 6 month change in readiness on a continuous scale for someone who continues to drink risky amounts is difficult, since it not clear how one would interpret a change in some number of points. Fourth, we did not adjust the level of significance for mul- tiple comparisons. As such one should be cautious about interpreting associations, particularly those not in the hypothesized direction. Lastly, all data were obtained from interviews and are subject to recall and social desir- ability biases. But interviews with trained research associ- ates and assurances of confidentiality took place immediately after the primary care visit to maximize accu- rate recall and minimize bias. Nonetheless, we do not know what patients meant by discussions about alcohol, which could have been brief or extensive and may or may not have included known effective components of brief interventions. Conclusion Our results provide important information. First, subjects appear to change readiness, importance and confidence after a single physician visit. Second, most patients with unhealthy alcohol use will improve 6 months after a pri- mary care visit, either on behavioral change constructs or drinking. Third, factors usually associated with worse alcohol treatment outcomes (e.g. drug use, alcohol related problems) do not seem to prevent improvement. Future research should focus on specific measures of behavior change constructs, perhaps assessed by ecological momentary assessments of these rapidly changing dimen- sions [47,48] and what contributes to their changing, and how and when they contribute to actual behavior change. A better understanding of these mechanisms could be used to enhance interventions for unhealthy alcohol use in primary care settings, which at present, are only mod- estly effective. But even if the reasons for the improve- ments in drinking and behavior change constructs are mostly unknown, primary care physicians should be aware of the prognosis for patients with unhealthy alco- hol use, to recognize incremental steps towards change and to support their patient's efforts. Competing interests The authors declare that they have no competing interests. Authors' contributions NB, NH, and RS conceived and designed the study. RS led implementation of the SIP study randomized trial. NH led and programmed the statistical analyses. NB wrote the first draft of the manuscript. All authors read and approved the final manuscript. Acknowledgements Nicolas Bertholet was supported by the Swiss National Science Foundation, and Fondation Suisse de Recherche sur l'Alcool. The Screening and Inter- vention in Primary Care (SIP) study was supported by a Robert Wood Page 7 of 9 (page number not for citation purposes)