This study used a descriptive, cross sectional design to determine predictors of happiness among hemodialysis patients.
Setting and Participants.
In the current study, 200 patients, who referred to the main hemodialysis center in Qazvin province, were selected through a convenience sampling method based on inclusion and exclusion criteria. Participants met the inclusion criteria if they were aged over 18 years, under hemodialysis treatment for at least 6 months and willing to participate. Exclusion criteria were history of severe stress during the past month, having psychological problems according to the patient's statements or medical record, history of using psychotropic drugs and having severe physical problems which prevents the researcher from interacting with the patient.
Considering a type I error of 0.05 (confidence level of 0.95) and a type II error of 0.2 (power test of 0.80), the sample size was estimated as follows.
The final sample size of 200 was calculated due to the possible non-response rate of 10%.
The socio demographic checklist included the following variables: age, sex, educational level, marital status, employment status, financial status, number of dialysis per week, and history of any underlying diseases.
The dialysis adequacy was assesses using the parameter Kt/V. In this formula, K is the dialyzer clearance, t is dialysis session time, and V is the distribution volume of urea.
The Oxford Happiness Questionnaire
This questionnaire was first developed by Argyle and Crossland in 2002, and it measures one’s happiness through 29 items. Responding to each item is based on a 4-point Likert scale from a (0) to d (3). The overall score ranges between 0 and 87. A score between 40 and 42 is considered appropriate (26). This questionnaire was translated into Persian by Sharifi et al. in 1997, and its validity and reliability in Iran have been reported to be desirable using internal consistency and Cronbach's alpha of 0.91 by Alipoor and Noorbala in 1999 (27).
The Schneider's Life Expectancy Questionnaire
This scale was developed by Schnieder et al. in 1991 to measure hope in individuals aged over 15 years. The scale consists of 12 items in which responding to each item is based on a 5-point Likert scale strongly disagree to strongly agree. In this scale, hope is measured through 2 subscales of agency thinking and pathway thinking. 4 items measures agency thinking (2, 9, 10, and 12) and 4 measures pathways thinking (1, 4, 7, and 8). Items 3‚ 5‚ 7‚ and 11 are distractors intended to make the content of the scale less obvious. The overall score ranges between 8 and 64, and higher score indicates more life expectancy. The validity and reliability of the scale in Iran have been reported to be desirable using internal consistency and Cronbach's alpha of 0.89 by Golzari et al. in 2007 (28).
Data collection was done from April to May 2021. Ethical approval was obtained from the ethics committee of Qazvin University of medical science in Iran (IR.QUMS.REC.1399.516). Before data collection, written informed consent form was obtained from all the participants. The response rate was 100%, and 200 questionnaires were analyzed.
The collected data were analyzed using the Statistical Package for the Social Sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative variables were described using means and standard deviations (SD), and qualitative variables were described by frequencies and percentages. To determine the predictors of happiness, Pearson correlation coefficient was first run, and then, the variables which were significantly associated with happiness were included in the multivariate regression model. Statistical significance was considered at p<0.05.