BMC Public Health 2007, 7:27 http://www.biomedcentral.com/1471-2458/7/27 expressing their ill-health. Inhabitants in or immigrants from different countries communicate their health, partic- ularly mental health, differently [53,55-57]. The fact that the psychiatric illness variable was self-reported and not clinically validated was the most important limitation of the study. Self-reported health is a reliable indicator of health [5,6], preterm mortality [58-61], and health care need [62,63]. However, it has not been confirmed whether self-reported mental health is also a reliable indi- cator. It is likely that the prevalence of poor self-reported mental health is undeerestimated in the present study since the respondents are generally probably less willing to report a psychiatric disorder than a somatic one. Nevertheless, the additional testing of this variable by per- forming an analysis of the hospital admission data for mental disorders in the same population supported the results of the present study, confirming our assumption that self-reported mental health may be a good indicator of mental health. Moreover, self-reported mental health is associated with mortality as self-reported health is [64,65] and we therefore believe that self-reported mental health is a valuable indicator in population health monitoring. Another limitation of the present study is that the immi- grant groups focused on probably lacked homogeneity not only between themselves with regard to self-reported mental health and other characteristics (including histor- ical backgrounds, religion, language, and geography), but also within themselves. For example, the three Baltic FSU republics have joined the European Union and differ from the other FSU republics in many other respects. Therefore, it is difficult to say whether the results of the present study are fully applicable to immigrants from these now inde- pendent countries when considered separately from the whole FSU; thus this applies to the East European coun- tries. Nevertheless, immigrants with different back- grounds had to be combined in larger categories ("Other East European countries" and "The former Soviet Union") to achieve sufficient statistical power and to conduct the analyses in the present study. Poland was categorized sep- arately due to a large number of Polish immigrants in Sweden. The FSU was categorized separately due to differ- ences in the economy and health of the inhabitants of the FSU compared to other East European countries [14]. The limitations of the cross-sectional design of the present study prevented us from tracing any causal pathways between the migration of people from the former Soviet Bloc and self-reported mental health, and we could only speculate about the determining mechanisms behind the reporting of psychiatric illness and psychosomatic com- plaints. A lack of data on alcohol consumption was also a limitation for a study on self-reported mental health, although an adjustment of outcomes was made for smok- ing. The questionnaire was not specifically designed for the present study and we had to use the available data rather than collect our own. Additionally, it was not pos- sible to perform a clinical evaluation to test the reliability of the instruments because the design of the national sur- vey does not include a clinical examination or a clinical instrument. Finally, the sample size, especially of immigrants from the FSU, was small and possibly affected the significance of the analysis. However, in spite of its small size, it included immigrants from the various former Soviet republics, and the proportion of respondents was representative of all 25–84-year-old FSU immigrants who arrived in Sweden after 1944. The weighted mean population from our sam- ple was similar to the average number of persons of the same age and country of birth living in Sweden registered by Statistics Sweden during 1994–2001 (not shown). The strengths of the extensive SALLS data balanced the limitations. SALLS is performed annually by Statistics Sweden and is designed to obtain information about the Swedish living conditions of the Swedish population. Sta- tistics Sweden is a governmental statistical bureau with a long tradition of carrying out national surveys and analyz- ing the collected data. The data collected by Statistics Swe- den is used in multiple studies and for the national statistical reports. The reliability of the survey questions is high and the nonresponse is rather low. The nonresponse rate in SALLS during 1994–2001 was about 20%, mostly due to refusal to take part. In the earlier samples it was found that those who refused to participate (2/3 of non- respondents) had the same mortality rate as the respond- ents. Regretfully, it was impossible to estimate the particular nonresponse among the immigrants in this study because the sample in SALLS is not chosen accord- ing to the country of birth. A more detailed description of the SALLS can be found elsewhere [66]. Conclusion According to the findings of the present study, the influ- ence of country of birth on the self-reported mental health was profound and could not be explained by other health determinants, such as age, sex, marital status, social net- work, SES, or smoking. The self-reported mental health differed, however, among immigrants from the different former Soviet Bloc coun- tries. Unlike the immigrants from the FSU, immigrants from Poland and other East European countries generally had a twofold higher odds ratio for reporting psychiatric illness and psychosomatic complaints than adults born in Sweden after adjusting for demographic and socioeco- Page 10 of 12 (page number not for citation purposes)