Background
Quality of life (QOL) assessment is considered by health scholars as an important requirement for evidence based health care decision making and policy formulation for ageing population of the world. Therefore, QOL assessment is a part of routine health care packages in many countries to ensure effectiveness of health care or innovative interventions that targeted aged populations [
1,
2].
The ratio of aged to overall population of Iran as a transitional country is rapidly increasing and based on the 2016 demographic census’s results aged people constituted about 9.3% of the country’s population [
3]. Current pace of notable growth in the global ageing population demands an extensive source of health and social care. Therefore, without an intensive plan of action to address maintenance of aged people’s health, the anticipated costs could be unaffordable for many countries, families and individuals [
4].
QOL according to the World Health Organization (WHO)‘s definition is the self-perception of individuals’ current standpoint position in life with respect to what goals, expectations, standards, priorities, culture and value system they might have in their living ambience [
5]. Thus, the concept of QOL could reflect many aspects of life [
6] and its improvement might pose substantial effects on elder people’s life. In consequence; QOL measurement was endorsed as a reliable priority index to provide information about integrity and competence of a health care system in responding to the transitional needs of an aging population.
Application of a reliable and explicit tool to measure QOL of elder people is an imperative prerequisite in health systems and also for conduction of robust research projects [
7]. However; few instruments such as CASP 19 [
8] and OPQOL-brief [
9] have been introduced for use sparingly on a verity of methodological and applied grounds. The existent generic and disease-specific tools for QOL measurement, usually have limitations for application on aged people populations due to empirical evidence of measurement bias and little standardization [
10].
The WHOQOL-OLD as an explicit measurement instrument for QOL assessment was introduced by the WHO [
11] and has been validated for application in different languages and socio-cultural circumstances [
11‐
19] but not translated for use among Persian-speaking elder adults.
Preeminent advantage of the WHOQOL-OLD relative to other QOL assessment tools is its development through an extensive international cooperation [
8] that makes its cross-cultural application and comparison of the results remissible. Being an old-age specific measure, not having other nonexclusive tools’ impediments (e.g. being developed inherently for general or young age populations and problems arising due to the format of administration, consistency of responses) and its applicability for impact assessment of the public and health policies on elder people’s quality of life are other superiority aspects of the WHOQOL-OLD. The instrument therefore; can be considered as a unique data collection tool that retain the required configuration for ascertainment of best investment areas to enhance quality of life in aged populations [
8‐
11].
Main aim of this study was to translate and psychometrically appraise properties of the Persian version of the WHOQOL-OLD to provide a robust measurement instrument for application in akin studies of QOL on aged Persian-speaking populations in the Middle East region and other neighborhood countries. Thus, cross-cultural and international comparisons of the findings from studies in different populations will be applicable.
Results
Participants characteristics
Mean age of the study participants was 70.63 ± 8 and their mean WHOQOL-OLD-P’s scores was 77.72 ± 10.41. Other characteristics of the respondents were presented in Table
1.
Table 1Demographics characteristics of the study participants (n = 400) in the cross-cultural adaptation and psychometric validation of the World Health Organization quality of life- old module (WHOQOL-OLD) for Persian-speaking populations
Gender |
Male | 167 (41.8%) |
Female | 233 (58.2%) |
Marital status |
Married | 288 (72.0%) |
Non-married | 112 (28.0%) |
Educational level |
Illiterate | 71 (17.7%) |
Primary school | 126 (31.5%) |
Secondary school | 38 (9.5%) |
High school diploma | 23 (5.8%) |
Academic undergraduate degree | 104 (26.0%) |
Academic postgraduate degree | 38 (9.5%) |
Retirement status |
Retired | 166 (41.5%) |
Not retired | 234 (58.5%) |
Living status |
With spouse | 204 (51.0%) |
With spouse & children | 80 (20.0%) |
With only unmarried children | 14 (3.5%) |
With only married children | 40 (10.0%) |
With other relatives/friends | 8 (2.0%) |
Living alone | 54 (13.5%) |
Morbidities |
Hypertension | 250 (62.5%) |
Cardiovascular diseases | 96 (24.0%) |
Cancer | 16 (4.0%) |
Pulmonary diseases | 48 (12.0%) |
Diabetes | 161 (40.3%) |
Osteoporosis | 107 (26.8%) |
Arthritis | 237 (59.3%) |
Hyperlipidemia | 177 (44.3%) |
Feasibility
The study participants’ overall and subscales’ scores of the WHOQOL-OLD-P along with the test-retest reliability and internal consistency coefficients were tabulated in Table
2. The outputs of ceiling and floor effects’ analysis for overall and subscales of the instrument were also presented in this table. As indicated the estimated values are in the range of acceptable range.
Table 2The WHOQOL-OLD-P overall and subscales’ scores of the study respondents in the cross-cultural adaptation and psychometric validation of the World Health Organization quality of life- old module (WHOQOL-OLD) for Persian- speaking populations
Sensory abilities | 4 | 20 | 13.98 | 3.16 | −0.39 | −0.09 | 0.5 | 1.3 | 0.83 | 0.95 |
Autonomy | 4 | 20 | 12.67 | 2.63 | −0.18 | 1.03 | 0.8 | 1.3 | 0.75 | 0.95 |
Death and dying | 4 | 20 | 10.89 | 4.10 | 0.34 | −0.48 | 8 | 3.8 | 0.83 | 0.98 |
Social participation | 5 | 20 | 13.45 | 2.54 | −0.38 | 0.68 | 0.3 | 1.5 | 0.73 | 0.98 |
Past, present and future activities | 6 | 20 | 13.52 | 2.38 | −0.09 | 0.67 | 0.5 | 1.3 | 0.80 | 0.95 |
Intimacy | 4 | 20 | 13.20 | 2.93 | −0.33 | 0.45 | 1.3 | 1.8 | 0.78 | 0.90 |
Total | 44 | 114 | 77.72 | 10.44 | −0.22 | 0.87 | 0.3 | 0.3 | 0.82 | 0.91 |
Qualitative content and face validity appraisal
The WHOQOL-OLD-P was sent to a panel of experts for their feedbacks about the instrument items’ conceptual, cultural and linguistic appositeness. Based on the panelists’ given scores to the listed items’ attributes on a Likert type scale the CVI and CVR were estimated and the values were in the range of acceptable variability (0.88 and 0.86 respectively).
Quantitative construct validity appraisal
The conducted CFA in a sample of 400 Muslim and Zoroastrian older adults yielded an acceptable model fit with the six factor solution that was similar to the endorsed model fit for the original WHOQOL-OLD (χ2/df = 1.92, P < 0.001), RMSEA = 0.04, CFI = 0.94, TLI = 0.93, SRMR = 0.06).
Discussion
Main aim of this study was to verify psychometric properties of the WHOQOL-OLD-P for use on Persian-speaking older adults in Iran and probably other countries of the world. The study findings represented admissible reliability and construct validity of the instrument to be used for QOL assessment in research and conceivably in practice settings.
In the development of the original WHOQOL-OLD module, the interviewees’ scores were considered to exhibit floor/ceiling effects on the basis of the percentage of the respondents with maximum or minimum total scores that exceeds 20% [
11]. The WHOQOL-OLD-P by this categorization, connoted no substantial floor and ceiling effects, indicative of its discriminant ability identical to the findings of the other WHOQOL-OLD cross-cultural validation studies [
14,
17,
19,
32,
33]. However; in a number of previous studies a tendency towards ceiling effect [
11,
34,
35] in measurement of well-being, life satisfaction and QOL was suggested due to probability of rampant positivity bias [
8].
The estimated internal consistency measures of reliability (Cronbach’s alpha coefficient) for the total and subscales of the WHOQOL-OLD-P in the present study were in the acceptable range (> 0.7) [40] which is somehow consistent with the findings of other psychometric studies of the WHOQOL-OLD module on other socio-cultural contexts [
11‐
17,
19,
36]. The only observed incongruity among the conducted validation studies were low estimated internal consistency measure of the Cronbach’s alpha for the “social participation” subscale in the Australasian study [
37], for the autonomy subscale in the Spanish, German and Turkish studies [
12,
17,
19] and for the “past, present and future activities” subscale in the Norwegian study [
15].
The calculated ICC measure of reliability over time for both the total WHOQOL-OLD-P and its subscales’ scores were in the vicinity of acceptable range [
28] and similar to the findings of two other validation studies of the WHOQOL-OLD [
8,
16].
The identified 6-factor solution that best fitted the study data was congruent with the reported priori factor structure of the original scale [
11] and in the validation study of the Dutch version of the WHOQOL-OLD [
38], however; the hypothesized model structure of the instrument in other studies [
12,
13,
15,
16,
19,
32] were incompatible.
Regarding the obtained results in this validation study, it can be concluded that the WHOQOL-OLD-P’s application is feasible since no problem encountered in the data collection stage and a relatively limited time frame (6–8 min for older adults with academic education and 10–13 min for the rest of interviewees) was required to complete the scale on every individual participant.
Study limitations
The study sample in this research consisted of elder people with at least one to three diagnosed simultaneous chronic diseases who had been registered in the two primary health care centers in the city of Yazd, the capital city of Yazd province, central part of Iran. The purposively selected health care centers and therefore, non-probabilistic sample that was selected for inclusion might be limited representativeness of the study participants and restraint extrapolation and generalizability of the findings. Comparison of the within-subjects perceived QOL measures and association of the factors such as religion, age, gender, level of education and overall health status with the estimated QOL values were not speculated in this study. Therefore; interim data collection and analysis in future corresponding studies could add further detail and explanation about precipitating factors of QOL.
Iran is a multi-cultural, multi-religious and multi-ethnic country and the study findings might not be generalizable to elder people residing in the country’s other provinces and geographical areas due to socio-cultural diversities.
There is also possibility of the reporting bias based on the respondents’ willingness and ability to provide accurate responses especially concerning the length of the WHOQOL-OLD-P, although the concern was attempted to be mitigated by emphasis on the anonymity of the participants and allocation of proper time for interview.
Elder people who suffer from multiple chronic diseases are more likely to develop depression and therefore; tend to report lower quality of life [
38]. Such an impediment must be taken into account in interpretation of the study data.
Multidimensional nature of QOL and the effects posed by certain underlying factors warrant further research to examine how these circumstances might relate to self-reported quality of life among older people. QOL assessment by use of measures that actually highlight specific domains e.g. physical, emotional and social functioning or over emphasis on health-related aspect of daily life experiences may also cause bias especially in measurement of elder population’s QOL [
39]. Aged people themselves, might have a priority need or interest that could potentially be reflected in their responses to the items of QOL assessment instruments. The judgmental approach (which entails comparison between the respondents’ state in different time frames e.g. present to past) which is salient generally in health related quality of life assessment tools could also further contribute to ambiguity in reliable determination of QOL. A number of other baseline socio-demographic factors e.g. gender, being divorced, unemployed, migrant and bereaved might also have same or even higher impact on several dimensions of perceived QOL in aged populations [
39]. All these facets warrants interpretation of the QOL data with caution.
Introduction of a valid and reliable instrument for measurement of quality of life among Iranian and other Persian-speaking elder adults was the primary objective of this study. Taking into account all above mentioned limitations, the WHOQOL-OLD-P application could be recommended as an explicit instrument for measurement of perceived QOL as a proxy measure of aged people’s overall health in the Iranian and other Persian-speaking elder populations across the world. The WHOQOL-OLD-P application could enhance reliability of QOL assessment by a wide range of healthcare providers (HCPs) (e.g. nurses, psychologists, geriatricians) in primary health care centers, secondary and tertiary care providing settings (e.g. nursing homes, day care centers and hospitals). The instrument can be utilized in routine care provision activities or in assessment of influences a specific health condition or morbidity and also subsequent restorative therapeutic intervention might have on perceived overall QOL among the aged people. Other social care providing organizations could also use the WHOQOL-OLD-P for estimation of impacts their policies, services or targeted interventions might have on elder people within the Persian-speaking countries.
Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit
http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (
http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.