It seems particularly appropriate to measure HRQoL in OA patients because the chronic debilitating nature of this disease likely takes a considerable toll on HRQoL. If this is indeed the case, and it appears to beC:\Users\DR. CHRIS\Desktop\PART TWO\measurement of QOL in OA.htm - ref5, then the assessment of HRQoL in OA patients is critical because this chronic disease does not typically cause death, but has a substantial effect on health, fitness, and physical, emotional, and social functioning. Therefore, HRQoL is likely to be a good indicator of both the global effects of OA on a patient’s life, as well as the effects of treatment.32
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There are two basic approaches to measuring QoL; The generic and the disease specific instruments. The use of either of the instrument depends on purpose of assessment. The first which is the generic instrument measures broad aspects of QoL. These instruments are not designed to assess HRQoL relative to a particular medical condition, but rather to provide a general sense of the effects of an illness. Medical Outcomes Study Short-Form Health Survey (SF-36)is the best-known generic HRQoL instrument. It measures HRQOL along 8 different domains:
physical functioning, role limitations due to physical problems, bodily pain, general health perception, vitality, social functioning, role limitations due to emotional problems, and mental health.32 The WHOQOL-BREF used in this study, is an example of the medical outcome study instrument. Other generic instruments that have been used with OA patients include the Satisfaction with Life Scale, the Extended Satisfaction with Life Scale, and the Quality of Life Inventory.32
Generic measures allow for comparisons of HRQoL across a variety of medical conditions and, thus, can be administered to different populations to examine the impact of various health care/therapeutic programs on HRQoL. The major limitation of generic HRQoL instruments is that they do not assess potential condition-specific domains of HRQoL. Because of this, they may not be sensitive enough to detect subtle treatment effects.32
The second approach to measuring HRoL involves the use of instruments that are specific to a disease (e.g., osteoporosis), a population (e.g., the elderly), or clinical problem (e.g., pain).
Measures geared toward specific diseases or populations are likely to be more sensitive, and therefore, to have greater relevance to practicing clinicians. The Arthritis Impact Measurement Scale (AIMS) is a prime example of an arthritis-specific HRQoL instrument that has been developed. The AIMS measures physical, social, and emotional well-being along 9 dimensions including dexterity, mobility, pain, physical and social activity, and depression and anxiety.32
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2.9.2 Abbreviated World Health Organisation Quality of Life questionnaire - (WHOQOLBREF).
This is an abridged version of the WHOQOL-100 tool. It is a 26-item, validated scale for adults which assesses quality of life across four domains namely; physical (domain 1), psychological (domain 2), social relationships (domain 3) and environmental (domain 4).21 The WHOQOL-Bref produces a profile with four domain scores and two individually scored items about an individual’s overall perception of quality of life and health. The four domain scores are scaled in a positive direction with higher scores indicating a higher quality of life. These four domains are scored, labelled, and transformed to a 0 to 100 scale with the aid of a formula accompanying the tool. The higher the qualities of life score on this scale, the better the quality of life.21
2.9.3 Quality of life in adults with knee osteoarthritis
Osteoarthritis (OA), particularly at the knee, is a leading cause of disability in older adults. By 2025, the prevalence of knee OA is expected to increase by 40%, largely due to an aging
population and the obesity epidemic.39 The burden of knee OA on individuals, health systems, and social care systems is considered by many as a public health crisis.39 A current community study funded by the centre for disease prevention and control (CDC) in Johnston County North Carolina, estimated the lifetime risk of developing knee OA was 44.7%. Thus, OA poses a serious public health burden.112
Half of all disability among older persons has been attributed to OA.2 Osteoarthritis is associated with pain, functional disability and being homebound.2 It is a crippling disease that imposes significant economic burden on the society due to its effect on function and activities of daily living.36 According to CDC, OA of the knee is 1 of 5 leading causes of disability among non-institutionalized adults. About 80% of patients with OA have some degree of movement limitation
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and 25% cannot perform major activities of daily living (ADL). 11% of adults with knee OA need help with personal care and 14% require help with routine needs. About 40% of adults with knee OA reported their health “poor” or “fair”. 38 In 1999, adults with knee OA reported more than 13 days of lost work due to health problems. Knee OA ranked high in disability adjusted life years (DALYs) and years lived with disability (YLD).38
Measurement of health related quality of life (HRQoL) among patients with osteoarthritis helps the health care provider to understand the impact of the disease in the patients' own perspective and make health services more patient-centered.36 HRQoL is increasingly acknowledged as a valid health indicator in many diseases. A review of literature that focused on adults with arthritis, including OA, revealed a variety of factors that have been used to conceptualize quality of life.
These factors include: physical functioning, life satisfaction, pain, social functioning, role functioning, mental health (depression), general health status, and vitality. Compared with other chronic diseases, patients with musculoskeletal disorders report among the lowest HRQoL and those with knee OA report lower scores on every HRQoL parameter compared to age-matched norms.113 Studies addressing quality of life have demonstrated that on average, quality of life for adults with OA is lower than the general population and women reported significantly lower quality of life and physical function than men.113 The poor QoL observed in knee OA patients is due to stiffness, difficulty in movement due to loss of muscle tone, strength and stamina. Many people with OA also experience fatigue, poor sleep, anxiety, depression, social isolation, loss of work and financial difficulty. All these lead to general deterioration in quality of life.71
Not surprisingly, HRQoL progressively declines in knee OA patients, concomitant with the magnitude of disease progression. Identification of therapies that improve HRQoL in patients with knee OA may mitigate the clinical, economic, and social burden of this disease.113
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A large body of evidence substantiates lower HRQoL scores in knee OA patients compared to age-matched norms.114 Increasing joint pain, comorbidity and radiographic disease severity are inversely related to HRQoL in knee OA patients.114 As the disease progresses, HRQoL declines to levels significantly below that of the general population. Desmeules et al. reported mean Physical Component Summary (PCS) and Mental Component Summary (MCS) scores from the SF-36 (short-form 36) of 28 and 43, respectively, in 197 patients waiting for total knee arthroplasty (TKA); both of these values are well below the 25th percentile compared to age- and gender-matched normative values.115 Other studies have reported similarly low HRQoL in patients waiting for TKA.116, 117 Cock et al., in the U.S., found that elders with knee OA are more likely to report lower levels of QoL even with controlling the confounding variables of age, gender, race, education and income.118 Zakaria et al., in Malaysia, who measured QoL of OA by using SF-36, stated that patients with knee OA attending primary care clinics have relatively poor QoL.
Domains related to the physical health status show relatively lower score as compared to mental health component.36 The lower score in physical health component compared to the mental component were consistent with other studies, although they used different instruments (COOP/WONCA charts and Sickness Impact Profile). The authors consistently showed that people with OA of the knee had poor quality of life pertaining to the physical activities and overall health compared to the general population.36 Salafi et al. in Italy found that elderly patients with knee OA had significant lower scores of SF-36.119 Their findings is consistent with of Muaraki et al. in Japan, they found that knee OA was significantly associated with lower QoL scores among the elder women.120 Boonsin et al., in Thailand, stated that knee OA has a negative impact on QoL.121
Yildiz et al., in Nottingham, concluded that elderly patients with knee OA undergo a significant impact on multiple dimensions of QoL compared with healthy controls.122 Adegoke et al., in Nigeria in a cross-sectional comparative study of knee OA patients with their age matched control,
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did not observe statistically significant difference between the HRQoL of knee OA patients and the control.19 They concluded that, OA does not significantly affect HRQoL of Nigerians and gender has no influence on their HRQoL. These findings are contrary to previous studies from other part of the world. Plausible explanations for these differences may be due to a small sample size used in their study and lack of cross-cultural validation of translated versions of the survey questionnaire.19 Therefore a recommendation for more studies on the QoL of knee OA sufferers in Nigeria are required in order to draw a conclusive evidence
2.9.4 Factors affecting QOL of knee Osteoarthritis
Various factors affecting QoL of adults with OA have been identified in previous studies. These factors range from individual characteristics (age, sex, income, education, and ethnicity) biologic function (body mass index), symptoms (pain, stiffness, fatigue and depression), physical function, and general health perception to characteristics of the environment (social supports).113
Gabriel and Bowling contend that quality of life research, especially in adults with OA, should focus on the personal characteristics and circumstances as influential variables as well as the individual’s dynamic interactions with society.123 In a European study, Bowling and colleagues sought to define the indicators of quality of life in adults to attempt the development of a multidimensional model of quality of life based on the adults’ perceptions.123 The researchers focused on the extent to which global quality of life was influenced by health, psychological and social variables, and social circumstances. They found that social relationships and good health were among the top criterion of quality of life in adults aged 65 and older.123 Consequently, multiple factors influence quality of life of patients with OA.
Adegoke et al. did not find significant correlation between age, sex and ethnicity and HRQoL of adults with knee OA.19 Their findings were inconsistent with the findings in other studies. For example, Milli et al. and Resnik et al. observed that women with knee OA had lower HRQOL
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scores than men.19 Zakaria et al. also found a consistent observation where female respondents with knee OA were found to have lower scores in most of the QOL dimensions with a significant difference seen in physical functioning even after adjusting for other factors.36 This is similar to other studies and because of the higher prevalence of knee OA in women, this finding is of particular importance to the overall management of patients with knee OA. It has also been shown that being female and having joint stiffness were significant independent predictors of total patient expenditures related to OA.36
Findings in previous studies have shown varied correlations between education and QoL scores of patients with OA of the knee.36 For example, Zakaria et al. found that knee OA patient with higher education have lower QoL scores, even though other studies observed that more years of education were associated with better physical function.36
Income has also been observed to affects QoL of adults with knee OA. Findings of some studies showed moderate positive correlations between income and QoL scores.36 No significance association is found when comparing QoL with different employment and marital status in most studies.36 Pinthusorn and colleagues in a cross-sectional study to assess factors that influence life satisfaction among women in Thailand with OA reported a monthly income of $286 in majority of the subjects.124 Majority of subjects were found to have a low SES due to limited education received by the subjects.
Zakaria et al. observed age to be a predictor for declining of physical function (PF) in patients with OA of the knee. A significant negative correlation was found between age and PF, even after adjustment for other confounders.36 Chacon et al., in Venezuela, who measured QoL using the arthritis impact measurement scales in a version translated to Spanish, and found that the perception of QoL is negatively affected by increasing the level of joint pain, old age and low
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socioeconomic status in elderly patients with knee OA.125 Some authors reported an insignificant negative correlation between age, QoL and PF.126
Pain is considered as a major determinant of loss of function in individuals with OA. They limit their functional activities to avoid movements that exacerbate pain. This pain is exacerbated during activities of daily living.126 Alrushud et al. in Saudi Arabia, studied the impact of knee OA on the QoL, confirmed that the knee OA symptoms, especially pain, decreased patient's QoL.126 Previous studies have demonstrated that obesity is associated with limitations in activity, physical function, and quality of life in OA.126 Sharma et al. found a longitudinal relationship between greater BMI at baseline and poor Western Ontario and McMaster Universities Arthritis Index (WOMAC) function outcome over 3 years in patients with OA of the knee.127 In a Japanese study, Norimatsu et al. who studied factors predicting health related quality of life among community dwelling women with knee OA observed that obese women had a poor QoL than non-obese women on univariate analysis, but obesity was not related to the QoL score on multiple regression analysis.128 Zakaria et al. also found a significant difference between BMI and QoL scores in adults with knee OA. Most of the respondents with higher BMI of 30 and above have lower QoL scores.36 David et al. in a longitudinal study to determine the effect of obesity in the progression of knee OA, found a mean BMI of 30.6±4.7 kg/m2.129 Creamer et al who used WOMAC found a significant influence of obesity on function and pain.130 The association between BMI and the risk of developing knee OA was demonstrable in various other studies too. Overweight and obesity either lead to an excessive load increase or a medial displacement of the resultant force, depending on the strength of the counteracting lateral muscles. Weight loss has been shown to reduce the incidence of knee OA in a cohort study and is one of the most important preventable risk factors for the knee OA.36
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Psychological reactions, like depression, helplessness and anxiety, in patients with knee OA are not surprising given the amount and persistence of pain and disability they experience and the uncertainty about what the future might hold for them.126,131 It has been reported that 10% of the people with OA are depressed, which is affecting their activities of daily living and restricting their lives.132 Depression or anxiety are frequently expressed when a person fails to cope with the pain and disability resulting from OA. Alrushud et al. observed that role limitation due to emotional problems domain is the most affected domain by knee OA.126
Comorbid conditions are common in patients with osteoarthritis and may contribute to disability.
A recent cross-sectional study reported that comorbidity severity was associated with more limitations in activities in elderly patients with hip or knee osteoarthritis.128 Hypertension and diabetes are common chronic diseases in the middle aged and the elderly in Nigeria and hypertension has been observed to be the most common comorbidities among patients with knee OA.133 Zakaria et al. showed majority of the respondents in the study had hypertension followed by diabetes, even though they didn’t find significant difference between comorbidities and QOL scores.36 The significant effect of epilepsy on QoL scores could be due to debilitating nature of this condition. Epilepsy has influence on patients, caregivers, siblings, work and other interpersonal relationships of everyone involved in the care of a member with epilepsy.134