1.1 Inclusion and exclusion criteria
The following inclusion criteria were used to optimize appropriate selection of articles:(1) written in the English or Chinese language; (2) articles that explored the concept of awareness of disease status among patients with cancer; (3) articles that explored the impact of disease awareness on patients’ quality of life; (4) randomized controlled studies, cohort studies or case control studies. The following exclusion criteria were used: (1) the conference abstract; (2) unavailable full text.
1.2 Patient and public involvement
No patient involved.
1.3 Literature retrieval and screening
We searched the following databases, Pubmed, CENTRAL(Cochrane Central Register of Controlled Trials), PsycINFO, WEB OF SCIENCE, Embase, CBM (Chinese Biomedical Literature database), WANFANG database (Chinese Medicine Premier), and CNKI (China National Knowledge Infrastructure). And the terms used are as follows: neoplasm, cancer, tumor, tumor, carcinoma, disclosure, truth telling, breaking bad news, knowledge, knowing, awareness, quality of life, QOL. And we also hand searched reference lists of obtained articles. If we couldn’t obtained the articles, we would e-mail the author. Pairs of reviewers independently screened literatures and the third reviewer resolved the disagreement. And the terms above had been complementary searched in February, 2018.
1.4 Data extraction and management
Pairs of reviewers independently extracted the data of included studies. The followindata was extracted: first author, publication year, country, journal, the setting where the research was carried out, the time when the study began and ended, the definition of exposure in the research, study design, financial support, conflicts of interests, patients’ characteristics and quality of life. The third reviewer resolved the disagreement.
1.5 Primary and secondary outcome measures
The included trials measured self-reported participant measures of QoL as primary or secondary end points.
General quality of life;
- physical function (e.g. performance of self-care activities, mobility, physical activities);
- social function(e.g. performance of work or household responsibilities, social interactions);
- role function(e.g. performance of daily life, amusement, hobbies);
- emotional function(e.g. sadness , anxiety, depression, negative affect);
- cognitive activity(e.g. performance of focusing attention, memorizing);
- vitality (e.g. energy and fatigue);
- economic function(e.g. financial difficulty)
2)Disease-related symptoms (or both)(e.g. fatigue, pain, dyspnea, insomnia, appetite loss, diarrhea).
1.6 Assessment of risk of bias in included studies
Pairs of reviewers independently assessed risk of bias of the included studies by the ROBINS-I assessment tool for non-randomized studies and the Cochrane risk of bias tool for randomized controlled trials. We resolved any disagreements by discussion or consulting the third reviewer.
1.7 Assessment of publication bias
If we included at least 10 studies in a meta-analysis, we generated funnel plots of effect estimates against their standard errors (on a reversed scale) by using Review Manager software (RevMan). We assessed potential risk of publication bias through visual analysis of funnel plots, with roughly symmetrical funnel plots indicating low risk and asymmetrical funnel plots hinting at high risk of publication bias. One should be aware that this is a rather subjective judgement, that funnel plot asymmetry might also arise from other sources and that publication bias need not lead to asymmetry in funnel plots. We further attempted to avoid publication bias by searching trials registries and conference proceedings for unpublished studies. We addressed duplicate publication bias by including only one studies with more than one publication. If we had doubt about whether multiple publications referred to the same data, we attempted to contact trial authors by email.
1.8 Grading of the evidence quality
Based on the results of the systematic review, the GRADE system is applied to evaluate the quality of evidence, which can be divided as follows: high quality (or A) : being very confident that the real effect value is close to the estimated effect value; Moderate quality (or B) : having moderate degree of confidence in the estimated value of the effect, the real value may be close to the estimated value, but there is still the possibility of large difference between the two groups; Low quality (or C) : the degree of confidence in the effect estimate is limited, and the true value may be quite different from the estimate;Very low quality (or D) has little confidence in the effect estimate, and the true value is likely to be very different from the estimate. Although evidence based on RCT is initially classified as high quality, confidence in such evidence may be diminished by five factors :(1) limitations of the study;(2) inconsistency of research results;(3) indirect evidence;(4) inaccurate results;(5) publication bias. Based on the same three factors, the evidence can be upgraded;(1) large effect value;(2) dose-effect relationship exists;(3) possible confounding bias may reduce efficacy.
1.9 Strategy for data synthesis
Measures of treatment effect: We analyzed continuous outcomes as standardized mean differences (SMD) between groups with a 95% CIs. For assessment of heterogeneity, we determined statistical heterogeneity by using the χ2 test. If heterogeneity was little (I2 ＜50%, P ＞ 0. 05), we had used the fixed effects model to calculate the combine effect. If heterogeneity was large,( I2≥50%, P≤0. 05), we had used the random effects model to combination of the studies. For assessment of reporting biases, we investigated for publication bias and other reporting biases by the using funnel plots.