To identify and review studies that measured whether telling the truth has a positive or negative effect on the patients' psychological distress, and to draw conclusions as to whether truth disclosure is beneficial or not in reducing psychological distress in palliative care patients.

The following databases were searched: MEDLINE from 1966 to December 2001; EMBASE from 1980 to March 2001; PsycINFO from 1966 to April 2001; CINAHL from 1982 to March 2001; Best Evidence from 1991 to January/February 2001; SIGLE from 1980 to January 2001; and the Cochrane Database of Systematic Reviews (Issue 1, 2001). The search terms used in each database were listed in the report. The Journal of Medical Ethics (1990 to 2000), reference lists of articles and grey literature (not defined) were handsearched. Studies reported in any language were considered.

Study designs of evaluations included in the review

The inclusion criteria were randomised controlled trials, controlled before-and-after studies, and interrupted time series. Most of the included studies had a cross-sectional design and control groups were rare.

Specific interventions included in the review

Studies of truth disclosure, defined as occurring when information on diagnosis, treatment and prognosis was given with no restriction to an individual with advanced cancer, were eligible for inclusion.

Participants included in the review

Cancer and/or human immunodeficiency virus (HIV). The inclusion criteria were palliative or terminally ill patients with cancer or terminally ill patients with HIV. In the studies included, the participants were cancer patients (or controls). However, the authors point out that it was not always clear whether all of the included patients were receiving palliative care. Studies in children under the age of 18 were excluded.

Outcomes assessed in the review

The outcome of interest was psychological distress following disclosure. The inclusion criteria were objectively measured or self-reported (validated instruments) patient outcome measures, and subjectively validated measures that had been tested for reliability. Claims for measuring the effect of truth telling on psychological distress were judged on the basis of the use of objectively validated measures of anxiety or depression. Studies that reported the patients' preferences for or against full disclosure were included if they also measured the impact of this disclosure on the patients' psychological well-being. Most of the included studies used self-report questionnaires or semi-structured interviews.

How were decisions on the relevance of primary studies made?

Three independent reviewers applied the inclusion criteria to each identified study and to the full-text versions of all selected papers. The decision on eligibility was by consensus.

For each included study, the authors commented upon methodological features related to quality, and the potential impact of these on the study's findings. The features described included: whether the aim and the inclusion and exclusion criteria were clearly stated; the method of accrual; exclusions and refusals etc.; adequacy of the sample size; baseline assessment; use of a control group; the definition and appropriateness of outcome measures; the validity and reliability of data collection tools; and the clarity of results.

A data extraction sheet was developed and the data were extracted by three reviewers independently.

The data extracted from the included studies included the following: the author, title, date and country; aim of the study; sample (participants); inclusion criteria; method; results; and the reasons why the study failed to meet the full inclusion criteria for the review.

How were the studies combined?

Other than a brief narrative overall conclusion, the included studies were not combined.

How were differences between studies investigated?

The inclusion criteria, characteristics of the participants, details of the methods used, and results were described separately for each of the included studies, along with the reviewers' assessment of the design and conduct of each study.

None of the identified studies fully met the inclusion criteria. Nine studies that represented the best available evidence were included on the basis that they attempted to measure the impact of truth telling or open disclosure on the psychological status of patients using valid outcome measures. The total number of participants in the nine studies was 901 (832 were cancer patients and the remaining 69 patients were part of control groups in two of the included studies).

No studies met the inclusion criteria for the review. Nine studies were described which offered the best available evidence on the psychological impact of telling the truth. Although a number of studies showed the patients' preference for full and open disclosure, there was no consistent evidence that providing full information about diagnosis or prognosis had an impact on psychological outcomes measured by validated measures.

No conclusive evidence exists to determine whether telling the truth has a positive or negative effect on the patients' psychological distress.

The review addressed a clear question in terms of the participants, intervention, outcome and study design. The search for studies was extensive and was not restricted by language or publication status. The inclusion criteria were applied by more than one person independently to minimise bias. The reasons why studies failed to meet the inclusion criteria were summarised, and full details of all the excluded studies are available from the authors.

In the absence of fully eligible studies, the authors presented the best available evidence. These studies were clearly presented in tabular format and summarised in the text. A method of validity assessment was not reported, but important features pertaining to validity were discussed for each included study in terms of the likely impact on the findings. It is appropriate that the included studies were not combined beyond a brief narrative summary, because there are more differences than similarities between them.

The authors' conclusions are consistent with the evidence presented.

Practice: The available evidence is contradictory. The authors state that practice and education could be informed if researchers coordinated their efforts to produce a group of rigorous studies with sound conclusions.

Research: The authors state that more rigorous studies are needed to provide evidence of the psychological impact of truth disclosure in patients with advanced cancer. In some settings, randomisation may be ethically justified; in other settings, before-and-after studies with an appropriate control group (perhaps of patients receiving a different diagnosis) may be the most rigorous design possible.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.