The variety of methods used in the reviewed studies makes comparison among them difficult. It would be important to achieve an agreement regarding what instrument is the most appropriate to employ in the case of caregivers of patients with schizophrenia in order to measure their QOL. In addition, future research is needed going beyond the cross-sectional design. It should be considered at least a case-control design having comparative groups clearly defined and blind (for QOL evaluator), or studies using self-report instruments to measure this construct and other variables in which disturbance variables are in control. This would allow obtaining better evidence about factors associated with QOL of caregivers of patients with schizophrenia.
Despite the fact that good quality evidence is required, a recent trend towards studying this subject on diverse family groups can be observed.
Regarding the aims of this review, some similarities were found in the results obtained from the studies reviewed:
a) What variables are related to QOL damage in caregivers of patients with schizophrenia?
Main variable was emotional burden on caregivers as a consequence of their role, lack of social and working support, course of the disease, and disruptions in family life. All these factors were associated with a considerable damage of QOL.
b) Does relatives' QOL differ substantially among developed and developing countries?
The feeling of being exhausted seems to be generalized to relatives from different countries as well as cost associated with mental disorders, however, major differences regarding QOL appear to be related to having a better access to and higher availability of health and economic resources for these caregivers. In developing countries, economic burden may be playing an important role in relative's QOL. Lack of psychiatrist, day hospitals, access to drug treatments, among others, could generate a considerable concern in these relatives.
c) Which objectives should aim at future researches?
There is a need for treatment and follow-up as much as improvements in family intervention programs delivered by health services. These factors should be considered in future research in this area. Program design should take into account socio-cultural characteristics of the population attending a health service. Efficacy of such interventions needs to be proved since they could be beneficial not only for the patients, but also for the caregivers.
This review has limitations. The study design of most reports was cross-sectional reflecting the lowest level of evidence. This has the following implications for the results:
a) Associations found across studies may have been influenced by different sources of bias making the internal and external validity of them questionable. For example, recruitment strategies and sampling varied a lot across studies. Most of the studies employed purposive samples where interviews were applied only to those who were willing to participate in a research. Therefore, caregivers studied may have not been a representative sample of caregivers of patients with schizophrenia.
b) The criteria adopted for including associations in the discussion might have excluded those that maybe were clinically significant but did not reach statistical significance.
c) The descriptive nature of most of the included studies made the use of quantitative pooling methods (e.g. meta-analysis) not possible. As mentioned previously, good quality studies are needed in order to assess the impact of interventions aimed to improve caregivers of patients with schizophrenia's QOL.
In summary, it seems that "informal care" is playing an important role in the care of patients with schizophrenia and this issue needs to be thoroughly analyzed because of the high psychopathological risk experienced by informal carergivers.