Data collection and analyses
The following databases will be searched:
➢ MEDLINE (via PubMed, 1946 to present),
➢ PsycINFO (via Ovid, 1806 to present),
➢ Web of Science including Social Sciences Citation Index and Science Citation Index Expanded (1900 to present),
➢ Cumulative Index to Nursing & Allied Health Literature (CINAHL) (via EBSCO Host, 1981 to present),
➢ Excerpta Medica Database (EMBASE) (via Ovid, 1974 to present),
➢ Cochrane Central Register of Controlled Trials (CENTRAL) (via Cochrane Library, 1948 to present),
➢ Physical Education Index (PEI) (via ProQuest, 1970 to present),
➢ and OpenGrey (1980 to present).
The search is restricted to studies published in English or German. Keywords will be related to PA, older adults, and eHealth interventions, using MeSH terms and other index terms, as well as appropriate synonyms. The keywords will be combined using the Boolean operation OR and AND. Validated RCT filters will be used for the searches in MEDLINE, PsycINFO, Web of Science, CINAHL, and EMBASE. For PEI and OpenGrey, no validated RCT filters are available. Therefore, appropriate keywords to identify studies using an experimental or quasi-experimental study design will be employed. For the search in CENTRAL, no RCT filter is necessary because the database only includes controlled trials. The search strategy is illustrated in Additional file 2 using the MEDLINE search as an example. References of the included studies will be searched to identify additional potentially relevant studies.
Selection of studies
One author will conduct the database search. First, titles and abstracts of studies identified using the search strategy outlined above will be screened independently by two authors to select the relevant studies. Any disagreements between the two authors will be discussed until consensus is reached. A third author will be involved in this discussion and will facilitate the process when necessary. In a second step, full texts of potentially relevant studies will be obtained and reviewed independently by two authors. Any disagreements between the two authors will be resolved by consensus and/or discussion with a third author. Screening of titles, abstracts, and full texts will be performed by uploading citations to the online systematic review software “Covidence” by Alfred Health.
Data extraction will be conducted independently by two authors. In case of disagreements that cannot be resolved by discussion, a third author will be involved. The following information will be extracted from the included studies: publication details (first author, year, title, country of study, funding source), study design, information regarding study methods (aim of study, inclusion/exclusion criteria for study participation, recruitment of participants, randomization procedure, statistical analyses, study limitations), participant characteristics (number of participants, number of withdrawals/excluded participants, mean/median age, age range, sex, ethnicity, existing risk factors for chronic diseases (e.g., type 2 diabetes)), intervention details (name of intervention, aim of intervention, number of intervention/control groups, intervention components and levels, delivery of intervention, intervention setting, duration of intervention, duration of follow-up, underlying theory), primary and secondary outcomes, outcome measurement, time points when data were collected, intervention effects on primary and secondary outcomes, and authors’ conclusions.
Assessment of risk of bias in included studies
Two authors will independently assess the risk of bias in the included studies by using the Cochrane Collaboration’s risk of bias tool . Potential disagreements will be resolved as outlined above.
A narrative synthesis of all relevant studies will be provided with tables of study and participants’ characteristics, details regarding intervention components and levels, outcomes, results, and authors’ conclusions. If feasible, a quantitative synthesis (i.e., meta-analysis) will be performed by using the random effects model because it is expected that the included studies will be heterogeneous in terms of intervention components and levels, physical activity assessment, and the comparator groups (i.e., non-eHealth intervention, no intervention). Heterogeneity will be assessed by visual inspection and calculating the I
2 statistics . Sensitivity analysis based on study quality and study design will be performed to determine the robustness of our results (i.e., studies considered as “low risk of bias” compared with studies considered as “high risk of bias”, RCTs compared with quasi-experimental studies). If a meta-analysis is not feasible, narrative synthesis for summarizing the evidence with regard to intervention effects, using harvest plots, will be performed .
If the selected data permit, a narrative and quantitative synthesis will be provided for the following subgroups and subsets of studies: subjective or objective assessment of PA, intervention access (computer, smartphone, or tablet), and intervention components and levels (e.g., information regarding recommendations for PA and benefits of regular PA, skills training/instructions, social comparison/social support, individual level vs. interventions incorporating or targeting features of the social or physical context).