Types of studies

All randomised trials (RCTs), quasi‐RCTs (RCTs in which allocation to treatment was obtained by alternation, use of alternate medical records, date of birth or other predictable methods), and cluster RCTs. We will also include cohort studies, controlled before and after studies, interrupted time series studies, qualitative studies and case studies.

Types of participants

The population was limited to people aged ≥ 15 years who had been diagnosed with CKD stage 5, or were in paid employment prior to starting dialysis; and family caregivers who were in paid employment prior to their family member starting dialysis. The review aims to include all types of dialysis treatment and study participants from low and middle income countries.

Types of interventions

• Vocational interventions

• Workplace adjustments

• Government policies

• Skills training

• Psycho‐social interventions

• Drug interventions

• Dialysis treatment interventions (e.g. dialysis modality: facility HD, home HD, PD)

• Dialysis equipment interventions.

Types of outcome measures

• Employment in a full‐time or part‐time capacity following dialysis initiation

• Unemployment, job loss or redundancy following dialysis initiation

• Time to return to work following dialysis initiation

• Durability ‐ or length of time employed

• Sick leave, disability pension rates / or disability pension duration

• Carers' allowance rates / or carers' allowance duration

• Change in household equivalised income.

Electronic searches

We will search the Cochrane Kidney and Transplant Specialised Register through contact with the Information Specialist using search terms relevant to this review. The Cochrane Kidney and Transplant Specialised Register contains studies identified from several sources.

1. Monthly searches of the Cochrane Central Register of Controlled Trials (CENTRAL)

2. Weekly searches of MEDLINE OVID SP

3. Handsearching of kidney‐related journals and the proceedings of major kidney conferences

4. Searching of the current year of EMBASE OVID SP

5. Weekly current awareness alerts for selected kidney and transplant journals

6. Searches of the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

Studies contained in the Specialised Register are identified through search strategies for CENTRAL, MEDLINE, and EMBASE based on the scope of Cochrane Kidney and Transplant. Details of these strategies, as well as a list of handsearched journals, conference proceedings and current awareness alerts, are available in the Specialised Register section of information about Cochrane Kidney and Transplant.

For non‐RCTs, we will also search MEDLINE, EMBASE, PsycINFO and NHS Economic Evaluation Database.

See Appendix 1 for search terms used in strategies for this review.

Searching other resources

1. Reference lists of review articles, relevant studies and clinical practice guidelines.

2. Letters seeking information about unpublished or incomplete studies to investigators known to be involved in previous studies.

3. Conference proceedings, government reports and theses.

Selection of studies

The search strategy described will be used to obtain titles and abstracts of studies that may be relevant to the review. The titles and abstracts will be screened independently by two authors, who will discard studies that are not applicable, however studies and reviews that might include relevant data or information on studies will be retained initially. Two authors will independently assess retrieved abstracts and, if necessary the full text, of these studies to determine which studies satisfy the inclusion criteria.

Data extraction and management

Data extraction will be carried out independently by two authors using standard data extraction forms. Studies reported in non‐English language journals will be translated as required, to facilitate assessment. Where more than one publication of one study exists, reports will be grouped together and all relevant study data will be used in the analyses. Any discrepancy between published versions will be highlighted.

Assessment of risk of bias in included studies

Measures of treatment effect

For dichotomous outcomes (e.g. employment, unemployment) results will be expressed as risk ratio (RR) with 95% confidence intervals (CI). Where continuous scales of measurement are used to assess the effects of treatment (e.g. duration of employment or unemployment; household income) the mean difference (MD) will be used, or the standardised mean difference (SMD) if different scales have been used.

Unit of analysis issues

The units of analysis in this review will vary depending on the outcome presented. We will adopt a person‐centred analysis in that we will report effectiveness of employment interventions in terms of the numbers of people employed, or the number who incur job losses, rather than numbers of jobs created or retained, or productivity gains.

Dealing with missing data

Any further information required from the original author will be requested by written correspondence (e.g. emailing corresponding author) and any relevant information obtained in this manner will be included in the review. Attrition rates, for example drop‐outs, losses to follow‐up and withdrawals will be investigated. Issues of missing data and imputation methods (e.g. last‐observation‐carried‐forward) will be critically appraised (Higgins 2011).

Assessment of heterogeneity

We will first assess the heterogeneity by visual inspection of the forest plot. We will quantify statistical heterogeneity using the I² statistic, which describes the percentage of total variation across studies that is due to heterogeneity rather than sampling error (Higgins 2003). A guide to the interpretation of I² values will be as follows.

• 0% to 40%: might not be important

• 30% to 60%: may represent moderate heterogeneity

• 50% to 90%: may represent substantial heterogeneity

• 75% to 100%: considerable heterogeneity.
  

The importance of the observed value of I² depends on the magnitude and direction of treatment effects and the strength of evidence for heterogeneity (e.g. P‐value from the Chi² test, or a confidence interval for I²) (Higgins 2011).

Assessment of reporting biases

If possible, funnel plots will be used to assess for the potential existence of publication bias (Deeks 2011).

Data synthesis

Data from RCTs will be pooled using random‐effects. Data from non‐randomised studies is expected to be heterogeneous, originating from different study designs and may not be suitable for pooling. In this case, effect estimates adjusted for confounding will be displayed in a forest plot. Data from qualitative studies, particularly regarding reasons for job loss will be reported using thematic synthesis following methods described by Thomas and Harden (Thomas 2008).

Subgroup analysis and investigation of heterogeneity

Subgroup analysis will be used to explore possible sources of heterogeneity. Sources of heterogeneity at study level could be type of dialysis, women or men, class of occupation, patients or carers, country of study or geographic region, social security or social insurance system, and employment interventions. Heterogeneity among participants could be related to age and co‐morbid status (e.g. < 50 years, with concurrent heart disease or cancer). Adverse effects will be tabulated and assessed with descriptive techniques, as they are likely to be different for the various interventions used. Where possible, the risk difference with 95% CI will be calculated for each adverse effect, either compared to no employment intervention or usual care.

Sensitivity analysis

We will perform sensitivity analyses in order to explore the influence of the following factors on effect size.

• Repeating the analysis excluding unpublished studies

• Repeating the analysis taking account of risk of bias, as specified

• Repeating the analysis excluding any very long or large studies to establish how much they dominate the results

• Repeating the analysis excluding studies using the following filters: language of publication, source of funding (industry versus other), and country.