Fig. 1 shows a summary of the inclusion and screening process. Databases and hand searches revealed an initial, 704 records. After duplicate records (n = 22) were removed, 682 records remained. Screening of titles and abstracts of these records resulted in the exclusion of 566 records that did not meet the inclusion criteria. In total, 116 articles were retrieved for detailed assessment. After screening these full-text articles, 94 articles were excluded, as they did not meet all inclusion criteria. The final number of articles included in the review was 22 (Fig. 1). Studies are grouped according to the instruments used. In total, these studies assessed QoL using seven unique instruments. The main characteristics of the 22 studies included are shown in Table 2.
<INSERT FIGURE 1 HERE>
Titles from databases and hand search (n = 704)
0
Titles from databases and hand search (n = 704)
Duplicates removed (n = 22)
00
Duplicates removed (n = 22)
Titles and abstracts screened (n = 682)
Titles and abstracts screened (n = 682)
Studies excluded (n = 566)
Title/abstract not relevant to answer research question (n = 558)
Manuscript not attainable (n = 8)
00
Studies excluded (n = 566)
Title/abstract not relevant to answer research question (n = 558)
Manuscript not attainable (n = 8)
Full text reviewed (n = 116)
Full text reviewed (n = 116)
Studies excluded (n = 94)
Disease-specific QoL instrument (n = 24)
Not conducted in African countries (n = 14)
Sample population not involving older adults >50years of age (n = 13)
Disease-specific population (n = 12)
Instrument not measuring QoL (n = 8)
QoLinstrument focused on care givers (n = 7)
Not a primary study (n = 6)
Instrument not described (n = 3)
Narrative literature review (n = 3)
Full article not attainable (n = 2)
No full text available in English language (n = 2)
00
Studies excluded (n = 94)
Disease-specific QoL instrument (n = 24)
Not conducted in African countries (n = 14)
Sample population not involving older adults >50years of age (n = 13)
Disease-specific population (n = 12)
Instrument not measuring QoL (n = 8)
QoLinstrument focused on care givers (n = 7)
Not a primary study (n = 6)
Instrument not described (n = 3)
Narrative literature review (n = 3)
Full article not attainable (n = 2)
No full text available in English language (n = 2)
Included 22 studies
0
Included 22 studies
Fig. 1: Schematic flow of search results
Research design
Out of the 22 studies included 18 (81.8%) were cross sectional studies; 2 (9%) were cohort studies [20, 21], and 2 (9%) studies had a longitudinal design [22, 23]. Of the articles included, 96% (n = 21) used a quantitative methodology.
Participants and settings
The number of participants included in any given study varied from 40 to 5131 subjects, totalling 29,505. The age range of participants from the studies included was between 50 and 94 years.
Most studies were conducted in South Africa (n = 7, 8957 participants), followed by Nigeria (n = 6; 2930 participants), and Kenya (n = 2, 3950 participants). Related to the countries Senegal, Angola, Ethiopia, Ghana, Lesotho, Tanzania and Tunisia, in each case, one study is included in this review. The community setting accounted for 18 of the included studies with the remaining four being from nursing homes or long-term care facilities. Two of the studies [45, 46] specifically studied slum settings. Of the 22 studies, one study specified that the instrument used was not suitable for illiterate people [24]. Another study did not report on the literacy of its participants [25]. The remaining 20 studies administered instruments to both literate and illiterate people. In these studies, the interviewer read out questions for illiterate participants and filled in their responses.
Instruments assessing QoL
In this review, 14 different instruments are found which were used to measure QoL in African countries in 22 different studies (table 1). The most often used instruments are the “World Health Organization Quality of Life Scale” (WHOQOL; n = 5) and the “Satisfaction with Life Scale” (SWLS; n = 4), followed by the “World Health Organization Quality of Life Scale-old version” (WHOQOL-OLD; n = 2), the “World Health Organization Quality of Life Scale-brief version” (WHOQOL-BREF; n = 2), the Short-Form Health Survey–36 (SF–36; n = 2), the “Short-Form Health Survey–12 (SF–12; n = 1), the “RAND 36” (n = 1), the “WHO-Study on Global Ageing and Adult Health-INDEPTH” (WHO-SAGE-INDEPTH; n = 1), the “Control, Autonomy, Self-Realization and Pleasure–19” (CASP–19; n = 1), the “Control, Autonomy, Self-Realization and Pleasure–12” (CASP–12; n = 1), the EuroQol–5D+C” (EQ–5D+C; n = 1); the EuroQol–6D (EQ–6D; n = 1), the “Currently Achieved Functioning” (CAF; n = 1), and the Aging Male Symptoms (AMS; n = 1). Four of these scales were used as a combination in two studies respectively: the SWLS and the CASP–19 [47] and the EQ–5D+C and the CAF [48]. The two studies that included slum settings both used the WHOQOL to assess QoL of participants [45, 46].
Reliability and Validity of instruments
According to 8 studies providing figures on reliability, 5 instruments had a Cronbach’s Alpha score of ≥0.7 (the SWLS (n = 3), the SF–12 (n = 1) and the WHOQOL-OLD (n = 1)), The study of Mugomeri et al. [32], using the WHOQOL-BREF reported reliability of 0.68 and the study of Hamren et al. [34] did not report on reliability of the full CASP–12 but on its subscales. Reliability of the subscales varied from 0.63 to 0.76. One instrument (SF–36) had good intra-class correlation according to the one study reporting on it [28]. Scores on interrater reliability were not provided and 13 studies did not report on any form of reliability. Most studies (n = 18) stated that the instrument used had content validity. Three studies, using the SF–36 (n = 2) and WHOQOL (n = 1) did not report on any type of validity (table 2)
Suitability of using instrument among illiterate population
Almost all, 90% of the studies, used interviewer administered questionnaires. This means that these instruments are suitable to use among an illiterate population. Out of these, three studies (using four instruments: the WHOQoL-old, WHOQoL-bref, SWLS and the CASP–19) used either as a self-completed or interviewer administered instrument in different studies. This means respondents could choose between self-administration or interviewer administration of the questionnaire. In two studies, one which uses a combination of the EQ–5D+C and CAF and the other study using the AMS, self-administration of the questionnaire was done.
Domains, time investment, and possibility for content modification
As shown in table 1, the domains of the instruments used varied. All instruments assessed physical and psychological aspects of quality of life. Only the CASP–12, EQ–5D+C, CAF, EQ–6D and the adapted AMS do not have a specific social domain included. Furthermore, the environmental domain was only captured in the different versions of the WHOQOL instrument. This domain is absent in the remainder of the instruments.
With regards to time investment, completion of the instrument varied from 2–6 minutes [35] to two hours [26]. However, most studies (n = 18) did not provide any information on time investment.
In some cases, adapting the instrument was needed to suit the participants or research settings. Content modification appeared to be possible in 20 studies. The studies reporting on the use of the EQ–6D [28] and the combination of EQ–5D+C and CAF [47] did not provide information about this possibility. In 13 studies, instrument translation or adaptation to the local language of the population was done before the use of the instrument. In the remaining nine studies, the instruments were administered without need for translation, because either a translated form pre-existed or mode of administration was in English language. Lastly, in nine studies (using the WHOQOL, WHO-SAGE-INDEPTH, WHOQOL-OLD, SWLS, CASP–12 and EQ–6D) researchers removed or rephrase original phrases of the instruments and inserted statements that would be familiar to the population in question [14, 22, 21, 30, 31, 32, 33, 34].