A cross-sectional hospital-based descriptive study was conducted at the outpatient department of Manmohan Cardiothoracic Vascular and Transplant Centre, Maharajgunj, Kathmandu, which is under Tribhuvan University, Institute of Medicine. It is a 100-bed capacity and designated center in the fields of Cardiac, Thoracic, and Vascular treatment in Nepal. It belongs to Bagmati Pradesh which has one of the highest warfarin users following rheumatic heart disease-related valve replacement. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines were strictly followed during the study.

The study population was the clients visiting the outpatient department of Manmohan Cardiothoracic Vascular and Transplant Centre, Kathmandu, and using warfarin therapy.

Non-probability purposive sampling technique was adopted to select the sample of 270 warfarin-using clients in the study. Clients using warfarin for the last two months were ascertained by checking the Outpatient Department (OPD) card or asking the clients waiting outside the OPD individually and interviewed as a sample unit.

Clients using warfarin medicine for at least two months, age ≥ 18 years, able to consent (both written and verbal) were included in this study.

The approval of the research proposal was obtained from the Research Committee of Pokhara Nursing Campus, Tribhuvan University (TU), and ethical clearance from the Institutional Review Committee (IRC) of Tribhuvan University, Kathmandu on feb 2, 2021 ref no. 261/(6-11) E2/077/078 The formal permission was taken from Man Mohan Cardiothoracic Vascular and Transplant Centre (MCTVC) for data collection through a request letter from Pokhara Nursing Campus.

Clients using warfarin medicine for at least two months, age ≥ 18 years, able to consent both written and verbal were included in this study.

The consent was both verbal and written. The participants were initially informed about the nature of the research verbally and then a written consent form was filled out and asked to sign by them if interested.

The required sample size for this study was calculated by using the following formula (standard deviation of mean for infinite population). ⁶ n = z α 2 . σ 2 d 2

Where,

n = Required minimum sample size

Z α = Significant value at α level of significance

σ = Standard deviation

d = Desired level of precision

The sample size was calculated based on the study done in Pakistan using the WHOQoL-BREF tool regarding Health-related quality of life among warfarin using patients having domain mean ± standard deviation of 64.27±26.28. ⁷

Applying the above formula in significant value for 95% confidence interval (Zα =1.96) and 5% relative error of the mean was 3.2135,

So, Required sample size n = 1.96 2 26.28 2 / 21.35 2 = 256.92 ∼ 257

This results in a minimum sample size of 257. After adding a nonresponse rate of 5%, the final sample size was 269.85 = ~270.

Hence, 270 final sample sizes had been calculated and considered for study purposes.

A structured interview questionnaire that included demographics, questions related to warfarin, and a brief version of the World Health Organization Quality of Life assessment tool (WHOQoL-BREF, 1996) to assess the health-related quality of life of warfarin-using clients.

WHOQoL-BREF consisted of 26 questions. Each question was rated in a 5-point positive direction (1=very poor, 2=poor, 3=average, 4=good, 5=very good) but questions Q3, Q4, and Q26 were negatively phrased. Higher scores denote higher quality of life. Clients were requested to respond to the questions related to the aspects of life experienced in the last four weeks. Questions 3 to 26 were divided into 4 different domains; the physical domain; the psychological domain; the social relationship domain, and the environmental domain.

Data were analyzed based on the transformed score. All four domains were taken into consideration to evaluate the overall quality of life.

The questionnaire was pre-tested in Shahid Gangalal National Heart Centre in 10% (26 clients) of the minimum required sample size and high internal consistency was found with 0.879 Cronbach’s alpha coefficient. The modification was done only in warfarin-related questions i.e. side effect (menorrhagia) based on findings of pre-testing.

Hospital authorities including the research and nursing departments were briefed about the study. The researcher visited the clients who were waiting outside the OPD. Clients using warfarin (≥2 months) and age ≥18 years were ascertained by checking the Outpatient Department (OPD) card and asking the clients waiting outside the OPD. Each client was explained about the purpose of the study and requested voluntary participation. Both verbal and written consent were taken from participants before conducting the interview. Information from participants was collected by the researcher herself using a structured interview schedule after proper instruction about the questionnaire. Confidentiality was maintained by using code numbers on each questionnaire. The research room was used during the interview to maintain privacy. The average time taken to complete the interview for one participant was approximately 20-25 minutes and each day 10-14 clients were interviewed. The duration of data collection was four weeks from 10 February 2021 to 10 March 2021. The response rate was cent percent. The data was collected on working days.

After complete data collection, data was checked for completeness and accuracy. Data was then coded and entered on the same day of data collection. Data was entered using EPI-DATA version 3.1 and transferred into Statistical Package for Social Sciences (SPSS 16 version) for further analysis. Both descriptive and inferential statistics methods were used to analyze the data.

Descriptive statistics were used to evaluate the demographic variables, warfarin-related variables, responses on WHOQoL-BREF items, domain scores, and level of quality of life of the clients. The chi-square test was used to identify the association between the health-related quality of life among warfarin-using clients and selected variables and the correlation coefficient was used to identify the relationship between each domain to overall HRQOL.

The findings of the present study resulted in a mean score (55.60±10.25) for overall quality of life among warfarin-using clients. More than half (64.8%) of the clients had a moderate level of quality of life (45-65). Likewise, 18.9% had a relatively high quality of life (>65) and 16.3% had a low quality of life ((δ45). A relatively high quality of life (65.00±16.00) was observed in a study conducted in France ⁸ among long-term vitamin K antagonist users. Similarly, a study conducted in Malaysia regarding health-related quality of life among atrial fibrillation patients using warfarin therapy resulted relatively high mean score (69.3±16.3) for overall quality of life. ⁹ Another Malaysian study also showed a relatively high mean score (68.7±11.30) on overall quality of life in warfarin users. ¹⁰

The present study evaluates the HRQoL of warfarin using clients based on mean scores obtained from each domain of WHOQoL-BREF. In this study, the highest mean score is found for the social relationship domain (64.17±11.5). The study conducted by Almeida et al. in Brazil also resulted in the highest mean score (80.4±23.8) for the same domain. ¹¹ The mean score for the social relationship domain was found similar to the present study in the study conducted in Pakistan (64.27±26.28), Malaysia (63.35±27.06), and Saudi Arabia (64.46±26.19). ^{12 – 14} However, contradictory findings (mean score 49.0±10.7) were obtained from the study conducted in Malaysia for the same domain. ¹⁰ The highest mean score for the social relationship domain in our setting might be due to better personal relationships and satisfactory support from family and friends.

Likewise, the mean score for the physical domain is found lowest (47.08±14.39) among all four domains of WHOQoL-BREF in this study which is consistent with the findings of the alike studies conducted in Malaysia (61.14±15.96), Pakistan (62.44±15.36), and Saudi Arabia (62.11±15.53). ^{12 – 14} In addition, the lowest mean score (44.0±9.6) for physical health was also found in a study conducted in Italy, ¹⁵ and two different studies in Malaysia (47.0±9 and 45.0±10.2. ^{10 , 16} In contrast, the highest mean score for their study in physical health (47.00±4.00) was found in the study conducted in Turkey. ¹⁷ Experience of extreme physical pain, presence of comorbidities, poor sleep pattern, and compromised work capacity may have adversely affected the physical quality of life of warfarin-using clients.

Regarding the psychological domain in this study, the domain score ranges from 4.17 to 91.67 with moderate mean±SD (56.5±14.35) which is consistent with the findings (mean±sd 52.7±8.5 and 53.5±9.6) of the studies conducted in Malaysia for the same domain. ^{10 , 16} Relatively higher mean scores (68.58±16.11, 67.84±15.54, 68.20±16.11, and 65.33±17.50) for the psychological domain were found in the studies conducted in Malaysia, Pakistan, Saudi Arabia, and Turkey, which is also the highest mean score among four domains of their studies. ^{12 – 14 , 18}

Similarly, a moderate mean score (54.65±12.25) for the environmental domain is found in the present study with scores ranging from 18.75 to 87.50, which is consistent with the mean score for the environmental domain in the studies conducted in Malaysia (62.78±17.58), Pakistan (63.45±17.66) and Saudi Arabia (63.43±17.60). ^{7 , 13 , 14} Comparatively lower mean score for the environmental domain in the Nepalese context might be due to lower socioeconomic status, lack of information regarding therapy, poor recreational habits, and limited accessibility to health services, and transportation facilities.

This study resulted in a significant association between overall age (p=.015), sex (p=.007), place of residence (p≤.001), and socioeconomic class (p≤.001) with health-related quality of life of warfarin users. Relatively high quality of life was observed in the 24.7 percent younger group whereas a statistically significant association was observed in physical (p≤.001) and psychological domains (p=.002). This finding varies with the study conducted in Malaysia where a non-significant (p=.76) association was found with age. ¹³ Likewise, the findings of this study showed that male warfarin-using clients had better scores in all domains of QoL which is in contrast (p=.146) to the findings of a similar study conducted in Pakistan. ¹² This might be due to better control of males in household income and decision-making power in our context. Regarding the place of residence, urban clients had a significantly better quality of life in all domains except the social relationship domain (p=.159). Similarly, a higher mean score was found in the middle socioeconomic class (60.30±9.74 versus 52.41±9.34) in comparison to the lower socioeconomic class with overall quality of life.

Furthermore, a statistically significant association (p=.008) between quality of life and the presence of comorbidities was observed in the present study having better quality of life in clients with no comorbidities than those having various comorbidities in all domains except the environmental domain (p=.712). However, the study conducted by Iqbal et al. in Pakistan resulted in better and statistically significant findings in all four domains of QoL with p-value ranges from <.001 to.002. ¹² Comparatively better (56.88±10.16 versus 54.35±10.22) but statistically non-significant association (p=.308) was observed in those with controlled INR levels which is consistent with the findings of the study conducted in Spain (4.9±1.0 versus 3.6±1.3). ¹⁹

The findings of the present study resulted in a moderate positive correlation between overall quality of life with perceived quality of life (r=.419, p≤.001) and health satisfaction (r=.505, p<.001). Similarly, strong positive correlation between overall quality of life and psychological (r=.794, p≤.001), environmental (r=.777, p≤.001), physical domain (r=.768, p≤.001), and moderate positive correlation with social relationship domain (r=.545, p≤.001) was observed in this study. This finding was supported by the study conducted in Pakistan which showed a positive relationship (correlation coefficient values range from 0.242 to 0.627, p≤.001) between each domain of QoL with overall QoL. ¹²

In this study exploration of subjective information might have been limited due to structured questionnaires. The generalizability of the findings might be limited due to a cross-sectional purposively selected single-setting sample. Respondents’ response bias might have influenced the overall result of the study.

The findings of the current study could help to inform healthcare professionals about the problems faced by warfarin-using clients and focus more on making their better quality of life while prescribing and providing holistic care throughout therapy. Findings might be supportive to concerned authorities to strengthen themselves for improving the quality of life of clients. This study also might serve as a baseline reference for concluding further studies on a similar subject.

Institutional authorities should conduct awareness programs for healthcare professionals and family members regarding the physical, psychological, social, and environmental health of warfarin using clients to improve their quality of life from time to time.

More emphasis should be given by the concerned authority while taking care of and counseling patients above 45 years, females, rural residents, those of lower socioeconomic class, and those who have comorbidities.

Further qualitative and multiple-setting research should be done for more generalizability.