Table 1 Eligibility criteria based on the PICO and PICo framework

Population (P)/participants (P)

Older adult, aged 60 years and over, and live in the community- or long-term care facilities

Intervention (I)/phenomenon of interest (I)

Meaning-centred intervention is defined as an intervention that aims to help individuals find meaning in their lives (1). Examples include but are not limited to logotherapy and existential therapy

Experience of meaning-centred intervention

Comparator (C)/context (Co)

The quantitative component of the review considers studies in which the comparison group received either an alternative intervention (e.g. acceptance and commitment therapy), no intervention, or waitlist control

Community setting and long-term care facilities

Outcome (O)

• The primary outcome of this review is loneliness

• Loneliness in this review is defined as a psychological state of distress or discomfort that results when one perceives a gap between one’s desires for social connection and actual experiences of it

• The other related outcomes include meaning in life, social participation, social isolation, social connections, suicide ideation, anxiety and depressive symptoms, social well-being). Studies on other outcomes not mentioned above are considered to give comprehensive insight into the impact of meaning-centred intervention on older adults. However, studies that do not evaluate the primary outcome are excluded. All outcome measures have to be evaluated at baseline and after the interventions