NEPHROLOGY - ORIGINAL PAPER

Psychometric assessment of the Persian version of the Ferransand Powers 3.0 index in hemodialysis patients

Tania Dehesh • Najaf Zare • Peyman Jafari •

Mohammad Mehdi Sagheb

Received: 11 June 2013 / Accepted: 2 August 2013 / Published online: 25 August 2013

� Springer Science+Business Media Dordrecht 2013

Abstract

Background This study aimed to assess the psychometric

properties of the Persian version of the Ferrans and Powers

3.0 quality of life index (dialysis type) in patients receiving

hemodialysis (HD) in order to describe their health-related

quality of life (HRQOL).

Methods The sample (n = 150) consisted of adult HD

patients receiving HD for at least 6 months from the

establishment of the study. A total of 88 men and 62

women, with an average age of 50.47, from Shiraz,

southern Iran, were enrolled in this study. The question-

naire was translated into Persian language using back

translation and bilingual techniques. Convergent, discrim-

inant, and construct validity of the Ferrans and Powers 3.0

dialysis version was evaluated. To check the internal

consistency of the data, Cronbach’s alpha, which indicates

the reliability of the data, was used for the entire ques-

tionnaire and for the subscales.

Results The convergent and discriminant validity and

success scaling rate for both sexes were 100 %. Cronbach’s

alpha was 0.95 overall, which was greater than 0.7 for all

the subscales except for the family subscale. Our results

suggest that HD patients in southern Iran have higher

HRQOL scores when compared with those in other coun-

tries. Despite the higher mean HRQOL score for men

compared with women, men had significantly higher

HRQOL scores only in the health and functioning subscale.

There was no significant correlation between HD patients’

HRQOL and educational level.

Conclusion The Persian version of Ferrans and Powers

3.0 has sufficient reliability and validity for measuring the

quality of life of Persian-speaking HD patients. Female HD

patients need more support and attention from family and

society.

Keywords Cronbach’s alpha � Ferrans and Powers

3.0 � HRQOL � HD � Persian

Abbreviations

HRQOL Health-related quality of life

HD Hemodialysis

ESRD End-stage renal disease

FA Family subscale of the HRQOL

HF Health and functioning subscale of the HRQOL

PS Psychological/spiritual subscale of the HRQOL

SE Social and economic subscale of the HRQOL

Background

Since 1960s, hemodialysis (HD) has been recognized as a

convenient approach to protect the life of patients with end-

stage renal disease (ESRD) [1]. In addition to the benefits of

HD, patients have to manage the adverse impacts of this

therapy [2] such as sleeping problems [3] and depression [4].

T. Dehesh � N. Zare � P. Jafari (&)

Department of Biostatistics, Shiraz University of Medical

Sciences, Shiraz, Iran

e-mail: jafarip@sums.ac.ir

T. Dehesh

e-mail: dehesht@sums.ac.ir

N. Zare

e-mail: najafzare@sums.ac.ir

M. M. Sagheb

Department of Internal Medicine, Nemazee Hospital,

Shiraz University of Medical Sciences, Shiraz, Iran

e-mail: saghebm@sums.ac.ir

123

Int Urol Nephrol (2014) 46:1183–1189

DOI 10.1007/s11255-013-0537-5

The causes of kidney failure are different based on the

region of origin. Diabetes mellitus and hypertension are the

most important causes of renal disease [1]. Definitely, HD

is one of the most advantageous technologies for the

treatment of ESRD patients [5]. However, overall mortality

rate for HD patients is high [6]; approximately 12,500

patients underwent HD in Iran in 2008 [7].

Recently, quality of life has been recognized as a fun-

damental issue that included some concepts such as phys-

ical functioning and patient’s sense of well-being [8–11].

Quality of life is arbitrated in combination of culture and

religion [12]. Numerous questionnaires have been used for

assessing the quality of life of HD patients [13, 14]. In

1985, Ferrans and Powers developed the HRQOL instru-

ment for patients with cancer. It has been modified to

evaluate HRQOL in many diseases such as diabetes, can-

cer, dialysis, stroke, cardiac and pulmonary diseases, epi-

lepsy, and liver transplantation. The HD version of this

questionnaire was extensively used in different countries,

such as USA [12], Hong Kong [15], Jordon [16], Taiwan

[17], and Turkey [18]. Several studies showed that HD

patients have lower HRQOL than the general population

[19, 20], and also, these patients have poor HRQOL

compared to other chronic illnesses [21]. The above

knowledge from the literature shows that the need to access

a reliable and valid Persian tool to measure HRQOL is

increasing extensively.

The aims of the present study were to translate the

English version of Ferrans and Powers 3.0 into Persian,

estimate its reliability, discriminant validity, and coverage

validity, introduce a valid and reliable Persian instrument

to measure HD patients’ HRQOL, and assess Iranian HD

patients’ HRQOL.

Materials and methods

This project recruited patients from a dialysis center and

two main hospitals that organize HD in Shiraz, which is

located in the southern part of Iran. During this case study

from July 2011 until December 2011, 160 patients received

HD on a thrice per week dialysis regime.

Inclusion criteria were as follows: (1) age more than 18

and (2) undergoing HD for at least 6 months. One hundred

and fifty patients fulfilled these criteria and were retained

until the end of the study. Demographic variables were

gender, age, and education level: (1) illiterate, (2) high

school proficiency, and (3) university knowledge. Some

clinical characteristics were also recorded.

Ferrans and Powers 3.0 is a free HRQOL questionnaire,

so we did not need permission from the developers. For-

ward–backward translation was conducted according to a

standardized guideline [22]. Forward translation was

carried out by a nephrologist and an English linguistician,

whose native language was Persian. The Persian version of

the questionnaire was then back-translated into the original

language by a native English speaker living in Iran who

was fluent in Persian and did not have any clinical

knowledge. The resulting questionnaire was then reviewed

during focus group discussions. The first Persian version of

the Ferrans and Powers 3.0 was pilot-tested in 10 patients

waiting for HD as part of a cultural adaptation process.

Since we asked the patients about the concept of the items,

it was clear that all items conveyed the designer’s purpose

and meaning to the responders adequately and there was no

need for any cultural adaptation. Ferrans and Powers 3.0

HRQOL [23, 24] was established based on the aspects of

life that a patient has satisfaction or dissatisfaction about

and how these aspects are essential or unnecessary to the

patient [25]. The questionnaire has 68 items, 34 items in

each area. Ratings are made from a 1-to-6 scale ranging

from very dissatisfied/unimportant to very satisfied/

important. The instrument yields four domain scores:

health and functioning (HF; 14 items), social and economic

(SE; 7 items), psychological and spiritual (PS; 7 items),

and family (FA; 5 items). Satisfaction responses are

weighted by their paired importance items. We refer to

these paired multiplicative (satisfaction/importance) item

scores as Q and then substitute these 34 Qs as an alternative

of 64 exact items to calculate subscale and overall scores.

In fact, we have 34 items for satisfaction and 34 items for

importance of those satisfaction aspects, thus 34 Qs that

will have the role of exact items in the calculations. The

range of overall and four subscale scores is between 0 and

30; higher scores indicate a better quality of life. Ferrans

and Powers 3.0 is a free questionnaire for assessing

HRQOL [26].

In this study, we did not perform test–reset analysis,

because of noncompliance of patients who had trouble

answering the questionnaire’s questions twice. Instead,

convergent, discriminant, and construct validity of the

Ferrans and Powers 3.0 for dialysis version of this survey

was assessed. To check the internal consistency of the data,

Cronbach’s alpha, which indicates the reliability of the

data, was used for the entire questionnaire and the sub-

scales. For checking the discriminant and convergent

validity, calculation of Spearman’s correlation matrix

between total HRQOL score and hypothesis subscale

scores is necessary. A correlation coefficient greater than

0.4 between each item and its own scale score is a symp-

tom of acceptable convergent validity [27–29]. Correlation

between an item and its hypothesized subscale scores

should be greater than correlation between this item and

other subscale scores, which shows discriminant validity.

Factor analysis was used for construct validity checking.

Quartimax was the best rotation to relate the highest loads

1184 Int Urol Nephrol (2014) 46:1183–1189

123

to each domain’s items. Cronbach’s alpha is the most

established statistic to check the reliability of the data. The

perfect reliability was shown by a[ 0.7 [28, 29]. Ceiling

and floor effects were assessed to find out the ability of the

questionnaire to detect clinical improvement. A ceiling

effect was cleared by 15 % or more patients scoring the

best possible scores, and the floor effect is the opposite of

ceiling effect [30].

T tests were used to determine the difference between

males and females. One-way ANOVA was used to

explore the difference in HRQOL based on educational

levels. All analyses were conducted using SPSS, version

16.0.

Results

The demographic features of the sample are included in

Table 1. On average, 2 out of 64 (3 %) items in each

questionnaire were missing. However, according to the

Ferrans and Powers 3.0 scoring algorithm, these missing

data effects were adjusted in the process of computing

HRQOL scores. Despite the existence of missing data in

some patients’ item responses, the complete scores in

each subscale and the whole of the questionnaire were

computable. From 150 patients, 88 (59 %) were male and

62 (41 %) were female. Education levels of patients were

classified into three levels as described in the ‘‘Materials

and Methods’’ section. The majority of patients in this

study had university background in their trainings (54 %),

and 19 % were illiterate. Overall, our patients were

middle-aged (50.5 ± 15.1 years old). Almost nearly half

of the patients had diabetes. The results of factor analysis

with Quartimax rotation are presented in Table 2. The

proportion of variance explained by the first four factors

was 89 %. All Q loadings are greater than 0.4 in their

domains. Items that were loaded in their original domains

exactly were bold-faced in the table, except Q15, which

was loaded on HF subscale instead of FA. Therefore,

construct validity of Ferrans and Powers 3.0 is completely

acceptable.

Spearman’s correlation matrix between all items and

hypothesized subscale is shown in Table 3. This result is

used for calculating discriminant and convergent validity in

Table 4. Correlations greater than 0.4 between an item and

its subscale score are acceptable for convergent validity,

and correlations less than 0.4 between an item and other

subscale scores are suitable for discriminant validity. Our

findings showed that the scaling success rates for dis-

criminant validity of the all items was 100 % (99/99), and

this was true also for all subscales. Convergent validity was

also 100 % for all domains.

Cronbach’s alpha for the total scales and four subscales

is reported in the first column of Table 5. Internal consis-

tency reliability for the entire questionnaire and for all

domains was supported by Cronbach’s alpha of 0.95, 0.88,

0.88, and 0.64 for HF, SE, PS, and FA, respectively, which

were greater than 0.7, except for the family subscale. The

overall mean of HRQOL and four subscale scores for HD

patients is also reported in Table 5. As shown in the second

column of the table, HF subscale has the lowest HRQOL

score, while the FA subscale has the highest score. In the

third and fourth columns of the table, HRQOL scores are

shown based on sex. A t test was used to explore whether

there is any significant difference in HRQOL based on sex.

The result revealed that there is no significant HRQOL

difference between males and females with the exception

of the HF subscale. The males had significantly better

HRQOL scores in the HF subscale (P = 0.01). The find-

ings indicate that both the ceiling and floor effects are

under 15 %, so the clinical improvement could be com-

pletely detectable.

The results of the comparison between educational

levels are presented in Table 6. One-way ANOVA showed

that educational level has no significant statistical rela-

tionship with HRQOL score (P [ 0.05).

The results of the comparison between the total and

subscale HRQOL scores with those in other studies are

shown in Table 7, showing that Iranian HD patients had a

statistically significantly higher HRQOL score overall and

in each subscale score than HD patients in Hong Kong and

have overall statistically significantly higher HRQOL

scores and also in the SE subscale score than HD patients

in Illinois (USA). As can be seen, there were no statisti-

cally significant differences between HD patients in

southeastern USA and Iranian HD patients in any subscale

scores and overall score.

Table 1 Demographic characteristics

Gender, N (%)

Male 88 (59)

Female 62 (41)

Educational level, N (%)

Illiterate 29 (19)

High school 40 (26)

University studies 81 (54)

Age, years (mean ± SD)

Total 50.5 ± 15.1

Male 52.3 ± 15.2

Female 47.8 ± 14.7

Month on HD C6

HD time (min) 216.5 ± 23.7

Diabetes, N (%) 57 (38)

Int Urol Nephrol (2014) 46:1183–1189 1185

123

Discussion

The Persian version of the Ferrans and Powers 3.0 has

adequate reliability, excellent convergence, and acceptable

discriminant validity for Persian HD patients, which are in

agreement with the other studies from other countries [12,

15–18, 31], but the majority of these studies used test–re-

test procedure to check instrument reliability. To the best

of our knowledge, ours is the first study to use convergent

and discriminant procedures for reliability checking of this

questionnaire. All scaling success rates in the assessment of

discriminant and convergent validity were 100 %.

Exploratory factor analysis of four factors showed excel-

lent construct validity. All items are completely loaded in

their domains, namely health and functioning, social and

economic, psychological/spiritual, and family. This out-

come supports the original domains that the designers had

obtained [22, 23] and shows that there is no cultural

antithesis between original English and Persian versions in

understanding the purposes of the items and that the

Table 2 Factor loadings

(rotated) of four factor solutions

of Ferrans and Powers 3.0

Extraction method: principal

components with Quartimax

rotation

Items belonging to the

postulated scales are bold-faced

F1: Health and functioning

F2: Social and economic

F3: Psychological/spiritual

F4: Family

Scale Item order F1 F2 F3 F4

Health and functioning

1. Own health 1 0.961 0.106 0.036 0.008

2. Health care 2 0.932 0.162 0.054 0.001

3. Leisure time activities 3 0.917 0.215 0.066 0.019

4. Physical independence 4 0.940 0.071 0.183 0.017

5. Effort for kidney transplant 5 0.901 0.254 -0.063 0.215

6. Diet 6 0.920 0.166 -0.028 -0.106

7. Standard living 7 0.955 0.106 0.091 0.030

8. Potential for a long life 8 0.915 0.180 0.185 -0.085

9. Sex life 12 0.970 0.109 0.045 0.004

10. Effort in family responsibility 17 0.965 0.139 0.078 0.023

11. Usefulness to others 18 0.941 0.200 0.021 0.059

12. Stress or worries 19 0.938 0.194 0.092 0.009

13. Funny activities 26 0.919 0.051 -0.025 0.029

14. Potential for a happy 27 0.783 -0.090 0.262 -0.075

Social and economic

1. Friends 14 0.353 0.808 -0.023 0.019

2. Emotional support from 16 0.339 0.684 0.054 0.067

3. Neighborhood 20 0.293 0.911 0.156 0.065

4. Home 21 0.266 0.933 0.104 0.099

5. Job 22 0.384 0.691 0.039 -0.040

6. Unemployment\retirement 23 0.250 0.842 0.179 0.138

7. Education 24 0.277 0.932 0.104 0.039

8. Financial independence 25 0.185 0.920 0.062 -0.010

Psychological/spiritual

1. Peace of mind 28 0.174 0.148 0.929 0.044

2. Personal faith in god 29 0.063 -0.035 0.980 0.077

3. Achievement of personal goals 30 0.251 0.139 0.922 0.045

4. Happiness in general 31 0.179 0.115 0.936 0.009

5. Satisfaction with life 32 0.107 -0.002 0.956 0.082

6. Personal appearance 33 0.106 0.015 0.981 0.022

7. Self in general 34 0.131 0.151 0.962 0.016

Family

1. Family’s health 9 -0.055 0.009 -0.004 0.965

2. Children 10 0.009 0.028 0.081 0.958

3. Family’s happiness 11 -0.013 0.139 0.081 0.906

4. Relation with spouse 13 0.108 0.017 0.051 0.990

5. Emotional support from family 15 0.070 0.023 0.068 0.917

1186 Int Urol Nephrol (2014) 46:1183–1189

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Table 3 Spearman’s

correlations between Ferrans

and Powers 3.0 items and

hypothesized scales

The correlation coefficient

between an item and its own

scale is shown in bold

Health and functioning includes

fourteen items (Q1–Q8, Q12,

Q17, Q18, Q19, Q26, and Q27),

social and economic includes

seven items (Q14, Q16, Q20,

Q21, Q22, Q23, Q24, and Q25),

psychological/spiritual includes

seven items (Q28, Q29, Q30,

Q31, Q32, Q33, and Q34), and

family includes five items (Q9,

Q10, Q11, Q13, and Q15)

Items Scales

HF Soc Ps Fm

Q1 0.91 0.28 0.20 0.20

Q2 0.89 0.29 0.22 0.19

Q3 0.91 0.32 0.19 0.16

Q4 0.88 0.31 0.24 0.15

Q5 0.85 0.35 0.18 0.18

Q6 0.91 0.30 0.25 0.18

Q7 0.89 0.30 0.19 0.17

Q8 0.91 0.33 0.27 0.16

Q9 0.10 0.32 0.18 0.82

Q10 0.05 0.36 0.16 0.75

Q11 0.02 0.29 0.24 0.85

Q12 0.88 0.32 0.24 0.18

Q13 0.21 0.42 0.25 0.82

Q14 0.37 0.89 0.34 0.30

Q15 0.89 0.34 0.31 0.79

Q16 0.29 0.89 0.33 0.25

Q17 0.91 0.32 0.20 0.15

Q18 0.93 0.32 0.24 0.18

Q19 0.88 0.41 0.23 0.18

Q20 0.33 0.89 0.35 0.32

Q21 0.27 0.91 0.39 0.35

Q22 0.37 0.77 0.30 0.31

Q23 0.26 0.79 0.27 0.32

Q24 0.28 0.87 0.39 0.37

Q25 0.28 0.83 0.29 0.23

Q26 0.91 0.28 0.24 0.19

Q27 0.89 0.26 0.31 0.18

Q28 0.23 0.38 0.91 0.35

Q29 0.16 0.29 0.88 0.21

Q30 0.32 0.35 0.92 0.26

Q31 0.25 0.34 0.91 0.16

Q32 0.24 0.34 0.94 0.27

Q33 0.23 0.33 0.91 0.22

Q34 0.18 0.34 0.92 0.23

Table 4 Item scaling tests: convergent and discriminant validity for Ferrans and Powers scales

Scale No. of items Convergent validitya Discriminant validityb

Range of correlation Scaling success (%) Range of correlation Scaling success (%)

Health and functioning 14 0.85–0.93 14/14 (100) 0.15–0.41 42/42 (100)

Social and economic 8 0.77–0.91 8/8 (100) 0.23–0.40 21/21 (100)

Psychological/spiritual 7 0.88–0.94 7/7 (100) 0.16–0.38 21/21 (100)

Family 5 0.75–0.85 5/5 (100) 0.02–0.89 15/15 (100)

a Number of correlation between items and hypothesized scale corrected for overlap C0.4/total number of convergent validity testsb Number of convergent correlations significantly higher than discriminant correlations/total number of correlations

Int Urol Nephrol (2014) 46:1183–1189 1187

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Persian translation conducts the designers purposes and

meanings to the responders perfectly.

We found that internal consistency reliability was sup-

portable by a Cronbach’s a[ 0.7, which is approximately

the same as in, or better in some subscales than in, other

studies [12, 15–18, 31]. HRQOL mean scores revealed

relatively high mean scores for the entire and four sub-

scales, which shows that HD patients have satisfactory

HRQOL in Iran. The results showed that subjects’ quality

of life is least with the HF subscale, but best with FA. A

possible explanation for these findings is that these patients

have to deal with a severe chronic illness and the most

important problem that they have is lack of health, so our

natural expectation was to have the lowest score in the HF

subscale, which is in accordance with the findings of Fer-

rans and Powers who explained that HD patients have to

change the goals of their life, and this has a greatest impact

on their HRQOL. But patients’ family has made adjust-

ments to help him/her [12].

Another issue is that our results implied that men have

higher mean HRQOL scores compared with women in all

subscales, except for FA, although without statistical

significance. A possible explanation is that healthcare costs

have a huge burden on HD patients [29] and men are

mostly responsible for the family’s economical situation,

so a low income because of illness decreases their HRQOL

score. By univariate analysis, we found that education does

not have significant effect on HD patients’ HRQOL, which

is negated by other researchers [12].

Although our findings report significantly higher

HRQOL scores than some studies on HD patients in other

countries, this is only a statistical comparison and does not

have enough validation for making judgment for whole

HRQOL scores between HD patients in these countries. In

fact, we were not able to correct potential confounders,

which can explain these differences, such as clinical con-

founders. Thus, these statistically significant differences

may have no clinical importance. For a more precise

comparison, more information is necessary and adjusting

the effect of such important confounders may change the

results completely. This can be done in future studies. In

this study, the compliance rate was 100 %, because the

people who assembled the questionnaire waited for each

patient until all items were completed. This study has some

Table 5 Cronbach’s alpha for mean and SD of the patients’ scores

Scale Cronbach’s

a% at

ceiling

% at

floor

Total mean

(SD)

Female mean

(SD)

Male mean

(SD)

Significant

Total 0.95 0 0 21.77 (4.09) 21.31 (3.83) 22.10 (4.25) P = 0.25 df = 148 t = -1.17

Health and functioning 0.88 0 0 19.53 (6.06) 18.52 (5.81) 20.59 (6.55) P = 0.01 df = 148 t = -2.61

Social and economic 0.88 0.02 0 23.24 (5.29) 23.56 (5.31) 23.02 (5.30) P = 0.54 df = 148 t = 0.62

Psychological/spiritual 0.84 0.02 0 21.69 (6.36) 21.95 (6.31) 20.51 (6.60) P = 0.17 df = 148 t = 1.37

Family 0.64 0.3 0 26.19 (5.49) 26.67 (5.26) 25.86 (5.65) P = 0.37 df = 148 t = 0.89

Table 6 Mean and SD of

patients’ scores based on

educational level

Education Mean (SD) Significance

Illiterate 21.44 (4.147) P = 0.83 F = 0.19

High school proficiency 22.055 (4.201)

University knowledge 21.75 (4.064)

Table 7 Comparison between HD patients’ HRQOL in Iran and some other countries

Iran (Shiraz)

n = 150

USA (Illinois)

n = 349 (Ref. [12])

Southeastern USA n = 70

(Ref. [21])

Hong Kong n = 80

(Ref. [15])

Mean (SD) Mean (SD) P value Mean (SD) P value Mean (SD) P value

Total 21.77 (4.09) 20.70 (4.77) 0.01* 21.14 (4.87) 0.30 17.30 (3.50) \0.01*

Health and functioning 19.53 (6.06) 18.64 (5.71) 0.12 18.92 (5.48) 0.47 16.40 (4.40) \0.01*

Social and economic 23.24 (5.29) 21.29 (5.41) \0.01* 21.57 (5.81) 0.06 17.30 (4.30) \0.01*

Psychological/spiritual 21.69 (6.36) 21.60 (6.37) 0.88 22.96 (5.73) 0.16 17.70 (4.40) \0.01*

Family 26.19 (5.49) 25.25 (5.07) 0.06 24.71 (5.40) 0.06 20.30 (4.50) \0.01*

* P \ 0.05

1188 Int Urol Nephrol (2014) 46:1183–1189

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limitations. Some confounding factors such as predialysis

therapy or disease trajectory, which may have affected the

results, were not controlled. Research in this field could

raise the opportunity to test such confounders.

Acknowledgments This work was supported by the Grant Number

89-5299 from Shiraz University of Medical Sciences Research

Council. This article was extracted from the Master of Science thesis

of Tania Dehesh. We are also thankful to the referees for their

invaluable comments.

Conflict of interest The authors declare that they have no conflict

of interests.

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