**5. The structure of health-related quality of life measures**

Some HRQ0L measurements are as simple as asking the patient, "How is your quality of life?" [23]. This question can be asked in a straightforward or complex manner, with either option producing restricted results. HRQoL tools are often questionnaires with a number of elements or questions. Domains are made up of items (also sometimes called dimensions). The area of behavior or experience that is being measured is referred to as a domain or dimension. Mobility and self-care are two domains that can be combined to form physical function, sadness, anxiety, or wellbeing, which can then be combined to produce an emotional function domain. Because it comprises eight aspects rather than a single summative measure, the short form 36 (SF-36) is one of the finest ways for measuring HRQoL in chronic conditions. Physical functioning, Social functioning, Bodily pain, Role limitations caused by physical health problems (Role/physical), Role limitations caused by emotional problems (Role/emotional), Emotional well-being (Mental health), Energy/fatigue (Vitality), and General health perceptions are all evaluated by questions in the eight dimensions. These eight aspects can be summarized into two components: physical health component summary and mental health component summary. Physical functioning, role limitations due to physical health problems, bodily pain, and general health perception are included in the physical health component summary, whereas social functioning, role limitations due to mental health problems, and general health perception are included in the mental health component summary. Each of the eight dimensions expressly assesses the patients' quality of life, such as;

**Physical Function (PF):** The degree to which health restricts physical activities like walking, self-care, stair climbing, lifting, and workouts.

**Role Physical (RF):** The degree to which physical health interferes with work, such as completing fewer tasks and having difficulty executing activities.

**Body Pain (BP):** The severity of pain and how it affects one's ability to work.

**Vitality (VT**): is the difference between feeling energized and exhausted and worn out.

**Social Functioning (SF):** The degree to which physical or emotional difficulties obstruct social activity.

**Emotional Role (RE):** The degree to which emotional issues interfere with work, such as decreased time spent on activities and completing fewer tasks.

**Mental Health (MH):** General mental health, including depression, anxiety, behavioral-emotional control.

**General Health (GH):** The degree to which one can subjectively judge his or her health condition in comparison to that of a year ago, as well as the level of physical activity.

These eight components are added together to form overall HRQoL, allowing the level of HRQoL of patients/clients to be calculated. Each raw scale score was turned into a 0–100 scale after the score for each domain was obtained by adding each item under each domain. The overall HRQoL was then determined by multiplying each converted domain score by eight to get the overall HRQoL (number of domains). The higher the total score, the higher the quality of life; the lower the score, the poorer the quality of life. Scores of 45 poor/bad/low HRQoL, 46–65 moderate HRQoL, and > 65 relatively high HRQoL are used to interpret the final score for the total score [24, 25].

### **6. Predictors of health-related quality of life among patients with diabetes mellitus**

From the study conducted among patients with diabetes mellitus on follow-up at one of the public specialized hospitals in Ethiopia, age, sex, marital status, educational status, smoking history, feeling of stigma, co-morbidity status, chronic complication and body mass index (BMI) were the potential predictors of HRQoL. The study indicated that, the overall HRQoL of patients with diabetes on follow-up at the study area was found to be moderate. General health, mental health, bodily pain and vitality were the most affected domains of HRQoL [24].

The study participants' overall HRQoL was found to have a transformed mean score of 50.318.1, with minimum and maximum scores of 16.4 and 79.1, respectively. The study participants had the highest (63.234.4) mean score in physical functioning and the lowest (30.222.9) mean score in the overall health domain among the eight domains of HRQoL. When the HRQoL was decomposed into domains, general health, mental health, bodily pain, and vitality all had a mean score below 50, indicating that they were the most affected (**Table 1**).

Principal component analysis (PCA) was also used to construct two-component HRQoL scores, with 66.77 percent of the total variance explained. The mental component score had a higher mean score (51.7716.72), with a maximum score of 80.75 (Appendices A-C).

According to this study, socio demographic status (age, sex, marital status, educational status), socio cultural status (feeling of stigmatized), behavioral factors (history of smoking) and clinical factors (co-morbidity status, chronic complication and body mass index are some of the predictors of health-related quality of life for patients living with diabetes mellitus [24]. Multiple linear regression was applied for the final model after controlling for the potential confounders and multicollinearity using variable inflation factor (VIF) (**Table 2**).


*HRQoL: health-related quality of life; MCS: Mental Component Score; NSH: Nekemte Specialized Hospital; PCS: Physical Component Score.*

#### **Table 1.**

*The eight domains of HRQoL, the overall HRQoL and the two component scores of HRQoL with their mean score of diabetic patients at NSH, East Wollega, West Ethiopia, 15th April -5th June, 2019, (n = 215).*

#### *Predictors of Health-Related Quality of Life among Patients with Diabetes Mellitus DOI: http://dx.doi.org/10.5772/intechopen.99179*

Residence, economic position, occupation, type of diabetes, drug regimen, and duration of diabetes mellitus were not statistically significant predictors of healthrelated quality of life, as shown in the table above.

Controlling for all other independent factors, the multiple linear regression model revealed that a unit increase in age would likely reduce health-related quality of life of diabetic patients by 0.25 (= 0.25, 95% CI, 0.43.55, 0.07, p = 0.007). Other literatures also supported this finding [11, 26, 27]. This might be because of the physiological alteration of the patients as they got older. Older individuals are mostly limited in physical activities, coping with pain intensity and relief from pain [28]. However, findings from other parts of Ethiopia, South Africa and the Nordic countries were inconsistent with the current study result where age has no association with HRQoL [29–31].

Being male was positively associated with better HRQoL compared to their counter parts (*β* = 5.23, 95% CI, 1.10–9.36, p = 0.013). Literatures are inconsistently explaining in this regard [11, 12, 27, 32, 33]. This disagreement could be due to the gender impact as most of the time women are treated inferiorly. They are less autonomous in giving decision on behalf of their rights. Moreover, evidences showed that women were more likely affected by DM than males. Women also are more susceptible to the risk of central obesity when compared to men which in turn lead to the enhancement of the risk of complication of DM. This greatly reduces HRQoL of the clients [34]. As for marital status, being married was positively associated as it would likely increase the HRQoL by 5.30 units compared to those who were single controlling for all other independent variables (*β* = 5.30, 95% CI, 0.88–10.52. P = 0.046). The psychological stability and better social interaction when compared to those who are not in marriage would contribute for the association [29].

Regarding the educational level the respondents achieved, unable to read and write would likely decrease the HRQoL by 8.81 units (*β* = 8.81, 95% CI,-14.88 to 2.82, P = 0.004) compared to those who achieved college and above after controlling for all other predictors.

The history of smoking was found to affect the HRQoL status of the patients with diabetes. Having smoking history would likely decrease the HRQoL by 9.03 units (*β* = 9.03, 9 5% CI, 15.23- -4.69, P < 0.001) compared to their counter parts. Centers for Diseases Control and Prevention (CDC) and other study from USA indicated that Smokers are more likely to have central fat accumulation than non-smokers, and smoking is known to induce insulin resistance and compensatory insulin secretion responses, which could explain the increased risk of diabetes in those who smoke [35]. In the same way, feeling of stigmatized because of being patient with diabetes would likely decrease HRQoL by 5.25 units (*β*= 5.25, 95% CI, 8.94 to 1.56, P = 0.005) compared to their counterparts controlling all other predictors. Multifaceted restrictions that the DM patients are facing, for example, the amount, type and timing of food consumed would attribute to the unsuitability of their social interaction. This in turn leads to the poorer HRQoL.

The absence of co morbid conditions and chronic complications related to diabetes mellitus increased HRQoL compared to their counter parts. In both cases, the absence of the condition would likely increase the HRQoL by about 6 units. As for BMI, the increase in one unit of BMI would likely decrease the HRQoL by 3.56 units (*β*= 3.56, 95% CI,-6.94- -0.18, P = 0.009). This could be attributed that co morbid conditions are another challenge that could put the patients in disturbing conditions. Patients might seek healthcare for both or above diseases in which case they were emotionally diseased, the role due to emotional problem might be disputed. All the domains of HRQoL directly or indirectly would be affected. In another way,


*Dependent Variable: Overall health related quality of life, VIF: Variable Inflation Factor, VIF max = 4.16.*

*\**

*<sup>P</sup> <sup>&</sup>lt; 0.05. \*\*P <sup>&</sup>lt; 0.001, Adjusted R<sup>2</sup> = 0.536, F = 16.46.*

#### **Table 2.**

*Multiple linear regression analysis of diabetic patients on follow up at NSH, East Wollega , West Ethiopia, 15th April -5th June, 2019, (n = 215).*

*Predictors of Health-Related Quality of Life among Patients with Diabetes Mellitus DOI: http://dx.doi.org/10.5772/intechopen.99179*

those who developed chronic complications would also live under the double crisis. In one way, they felt unhappy about being patient with diabetes, and in another way, they would be under psychological, physical, emotional, social, and spiritual agony.

In conclusion, the present study identified that the HRQoL of patients with diabetes on follow-up at NSH was moderate. Domains of general health, mental health, bodily pain, and vitality were the most affected domains among the patients with diabetes. Sex, age, education status, marital status, history of smoking status, BMI, the feeling of stigma status, comorbidity status, and diabetic-related chronic complication status were predictors of HRQoL identified in this study.

It is recommended that health policy makers should give due attention for the overall HRQoL of the patients with diabetes on follow up at health institutions in addition to the existing treatment focused guidelines. Health care providers should also give emphasize to general health, mental health, bodily pain and vitality of the patients. Well scheduled, regular and continuous diabetic health education has to be provided as equally as important with the usual treatment and care for the patients. Respecting and understanding the patients' feeling has to be put first.

Moreover, health researchers should conduct further longitudinal studies with larger sample size in order to generalize the overall HRQoL of patients with diabetes at national level. Experimental and qualitative study design needs to be considered focusing the life style modification on patients with DM.

#### **Annexes**


#### **A. Correlation matrix**
