Predictors of Health-related Quality of Life among Warfarin Patients

Objective: Warfarin is amongst the most frequently used oral anticoagulant, that is often prescribed to control and prevent various thromboembolic diseases like venous thromboembolism, stroke, atrial fibrillation, and valvular heart disease. This study aimed to determine various predictors and their impact on overall HRQoL among warfarin patients. Methods: A cross-sectional study using WHOQOL-BREF research tool was conducted among warfarin patients. Data was collected by convenience sampling method. Descriptive, comparative, and inferential statistics were used by Statistical Package for the Social Sciences (SPSS) ver. 24 to determine the predictors of HRQoL among warfarin patients. Results: The majority of the studied warfarin patients were females than males (n=221, 69.3%, and n=98, 30.7% respectively). In univariate analysis, statistically non-significant differences (p >0.05) were observed in gender, age, marital status and work. In multivariate analysis, significant differences (p <0.05) were observed in education, warfarin usage, and warfarin therapy duration. Conclusion: These results indicated that education, warfarin usage, and warfarin therapy duration were the pure predictors of HRQoL among the studied cohort of the warfarin patients.


INTRODUCTION
Due to high inter and interpatient variability, warfarin is only effective if its therapeutic range is maintained and if its blood levels are above or below its therapeutic window, it exhibits greater risks of bleeding and thrombosis respectively [1,2]. It is a most frequently used oral anticoagulant, that is often prescribed to control and prevent various thromboembolic diseases like venous thromboembolism, stroke, atrial fibrillation, and valvular heart disease [3][4][5]. Due to its narrow therapeutic window, warfarin always requires frequent and careful laboratory monitoring to minimize or avoid bleeding complications and to obtain optimum therapy outcomes [5,6]. As a matter of fact, warfarin usually causes adverse drug reactions (ADRs) that sometimes require hospital admission and if the length of hospitalization is increased it may lead to morbidity and mortality among patients on warfarin [7][8][9].
Health Related Quality of Life (HRQoL) is not only measured in healthy individuals but also in patients to estimate the overall health status of the society which ultimately helps in designing and implementing healthcare policies to improve the overall health status of the society [10][11][12]. The HRQoL is a multi-dimensional model generally used to observe the impact of health status on individuals' quality of life [13,14]. The WHOQOL-BREF research tool has been used by plenteous studies conducted in different parts of the world to determine HRQoL of chronic disease patients as well as healthy individuals [10][11][12][13][14]. Though fewer studies across the globe are evident in the literature regarding the impact of warfarin therapy on disease outcomes, warfarin therapy duration and its anticoagulation control, the association of warfarin therapy duration and INR, treatment satisfaction and association of knowledge and beliefs with anticoagulation control [13][14][15][16][17][18][19][20] but in the studied population, nothing is reported regarding the effect of sociodemographic predictors on HRQoL using the WHOQOL-BREF among warfarin patients.
The WHOQOL-BREF tool is comprised of four different domains named physical, psychological, social and environmental domains [10]. This study aimed to determine various predictors like gender, age, marital status, education, work, comorbidities, warfarin therapy usage, and duration and their impact on overall HRQoL among warfarin patients.

MATERIALS AND METHODS
This was a cross-sectional study done and a self-administered questionnaire with WHOQOL-BREF tool were employed. The study subjects were screened for inclusion and exclusion criteria. For inclusion criteria, participants above 18 years, non-pregnant women and those who gave consent were included in the study. For exclusion criteria, those who did not meet the inclusion criteria were excluded from the study. At first, information sheet was handed to patients and informed consent was taken. The questionnaire was delivered personally to the patients by the researcher who also collected them back after they completed the study. The sampling method employed was convenient sampling. Content validity of the questionnaire was checked before start of the study. Reliability of the questionnaire was assessed using Cronbach's alpha which is the most common tool to be used to measure internal consistency.

Statistical Analyses
Percentages and frequencies were used for the categorical variables, while means and standard deviations were calculated for the continuous variables. Chi square, Spearman's correlation coefficient and multiple logistic regression were used to evaluate correlations and impact of various demographic variables on overall HRQoL of the studied warfarin patients. Data from the research questionnaire were analyzed using Statistical Package for the Social Sciences (SPSS) version 24.0.

RESULTS AND DISCUSSION
The demographic data of the patients are presented in Fig. 1. There was a total of 319 participants with more females than males (n=221, 69.3%, and n=98, 30.7% respectively). Around 106 (33.2 %) of the studied patients were less than 30-years of age whereas 213 (66.8%) were equal to or above than 30-years of age. A total of 4 (1.3%) warfarin patients had a primary level of education and 315 (98.7 %) had a higher level of education. A total of 85 (26.6%) warfarin patients had comorbidities and 234 (73.4%) didn't suffered from any comorbidity.   Education often advances self-learning and selfimprovement in general health states among patients. These could often enhance selfsatisfaction and result in improved HRQoL especially among chronic diseases patients like patients on warfarin. As a matter of fact, highly educated patients have better understanding of their disease states, drug doses, treatment regimens, and their disease understandings in general [21][22][23][24]. Moreover, to have optimum pharmacotherapy, highly educated patients are more likely to acclimatize their routine lifestyle and adopt preventive measures, resulting in improved therapy outcomes [24][25][26][27].
In our study, in univariate analysis, the higher educated patients had improved HRQoL (p <0.05) than the rest with less education. The apparent reason could be that an increase in drug or disease-related awareness may make patients more aware of their drug usage pattern, medication adherence, dietary controls, and lifestyle modifications which in return might increase their overall HRQoL. On the other hand, in multiple logistic regression analysis, statistically a non-significance (p >0.05) was observed when the confounders were adjusted. Conversely, in univariate analysis, according to the findings of our study, comorbidities, warfarin usage, and warfarin therapy duration had statistically significant associations (p <0.05) with overall HRQoL among warfarin patients. And multiple logistic regression analysis revealed that warfarin usage, and warfarin therapy duration were statistically significant (p <0.05) predictors of HRQoL among warfarin patients in the studied cohort of the patients.

CONCLUSION
In conclusion, our study highlights that education, warfarin usage, and warfarin therapy duration were the pure predictors of HRQoL among the studied cohort of the warfarin patients.

CONSENT
At first, information sheet was handed to patients and written consent was taken.

ETHICAL APPROVAL
It is not applicable.

ACKNOWLEDGMENT
This publication was supported by the Deanship of Scientific Research at Prince Sattam bin Abdulaziz University, Alkharj, Saudi Arabia.