|Year : 2019 | Volume
| Issue : 1 | Page : 14-19
Correlation between functional disability grade and radiographic severity among Nigerian patients with knee osteoarthritis
Umar AbdulAziz1, Olufemi O Adelowo2, Bello O Usman3
1 Rheumatology Unit, Department of Medicine, Faculty of Clinical Sciences, College of Health Sciences, Ahmadu Bello University Teaching Hospital Zaria, Kaduna State, Nigeria
2 Rheumatology Unit, Department of Medicine, Lagos State University Teaching Hospital, Ikeja, Lagos State, Nigeria
3 Department of Radiology, Faculty of Clinical Sciences, College of Health Sciences, Ahmadu Bello University Teaching Hospital Zaria, Kaduna State, Nigeria
|Date of Web Publication||31-Jul-2019|
Dr. Umar AbdulAziz
Senior Lecturer/Consultant Rheumatologist, Rheumatology Unit, Department of Medicine, Faculty of Clinical Sciences, College of Health Sciences, Ahmadu Bello University Teaching Hospital, PMB 06, Shika, Zaria, Kaduna State
Source of Support: None, Conflict of Interest: None
Background: Knee osteoarthritis (OA) is the most common form of degenerative arthritis in human and a leading cause of functional disability in the middle aged and elderly. The diagnosis of knee OA is often based on clinicoradiographic criteria. And in spite of the widespread utilization of knee radiograph in the diagnosis of knee OA, studies on the correlation between clinical and radiographic findings have been discordant. Although most studies of knee OA patients in Nigeria have incorporated knee radiograph in the diagnosis of the disease, the contribution of radiographic severity to functional disability in Nigerian patients is not well described. Objective: The aim of this article is to determine the pattern of radiographic knee OA in Nigerian patients and the correlation between radiographic grades of knee OA and functional disability. Materials and Methods: One hundred forty consecutive patients with knee OA attending the Rheumatology Clinic of Ahmadu Bello University Teaching Hospital were recruited for the study. Patients biodata and anthropometric parameters were ascertained. Patients had general and musculoskeletal examination. Knee radiographs were done for all patients and graded using the Kellgren-Lawrence (K-L) grading system. Pain and functional disability grades were measured using Likert 3.0 Western Ontario McMaster University index. Results: All 140 patients had definite knee OA on radiograph (K-L grade 2 and above). Grade 2 radiographic knee OA was noted in 51 (36.4%) patients, grade 3 in 71 (50.7%) patients, and grade 4 in 18 (12.9%) patients. Eighty-nine (63%) patients had severe radiographic knee OA. The mean pain and disability scores were significantly higher in patients with grade 3 or 4 radiographic knee OA compared to those with grade 2 radiographic knee OA. Both pain and functional disability moderately correlated with radiographic grades (rs = 0.36, P = 0.000) and (rs = 0.48, P = 0.000), respectively. Conclusion: The point prevalence of severe radiographic knee OA (K-L grade 3 or 4) is 63% in Nigerian knee OA patients. There is a moderate correlation between radiographic severity and functional disability in knee OA patients, with radiographic severity being an independent predictor of functional disability.
Keywords: Functional disability, knee osteoarthritis, radiographic grade
|How to cite this article:|
AbdulAziz U, Adelowo OO, Usman BO. Correlation between functional disability grade and radiographic severity among Nigerian patients with knee osteoarthritis. J Med Trop 2019;21:14-9
|How to cite this URL:|
AbdulAziz U, Adelowo OO, Usman BO. Correlation between functional disability grade and radiographic severity among Nigerian patients with knee osteoarthritis. J Med Trop [serial online] 2019 [cited 2020 Jun 7];21:14-9. Available from: http://www.jmedtropics.org/text.asp?2019/21/1/14/263747
| Introduction|| |
Osteoarthritis (OA) is the most prevalent rheumatic disease in the general population globally., Prevalence of OA widely vary among populations and depends on how the disease is defined, whether diagnosis is based on clinical, radiographic, or clinicoradiographic criteria. Most population surveys showed that the prevalence of radiographic OA and, to a lesser extent, clinical (symptomatic) OA increases steadily from the age of 40 years in males and 50 years in females, with the rate being consistently higher in women than in men.,,,,
Knee OA is a leading cause of functional disability, especially among middle-aged and elderly individuals.,, It is also a leading cause of loss of self-independence among those of middle to elderly age. Prevalence of functional disability in Nigerian patients with knee OA ranges from 50.6% to 90.2%., Several factors have been shown to impact on functional disability in knee OA; these include pain severity, presence, number, and severity of comorbidities,, low educational status, and radiographic grade., Of the several factors that have been proven to be associated with functional disability in knee OA patients, the correlation between radiographic severity and functional disability is perhaps the most discordant. Although some studies have shown modest association between radiographic and clinical severity indices like pain and functional disability,,, other studies showed limited or no association between the extent of pain and functional disability vs. radiographic severity., Reasons given by researchers for the discordance seen between radiographic changes and clinical symptoms include lack of uniformity and standardization of research methods utilized, the confounding and diluting effects of several factors that contribute to symptoms in knee OA patients and poor adjustment for such confounders, usage of small sample size in some knee OA research and limitation in radiological studies done due to noninclusion of patellofemoral radiograph,, and lack of utilization of clinimetric assessment tools in assessment of functional disability., The difference in prevalence of radiographic grade in populations studied is also thought to contribute to lack of correlation between radiographic and clinical OA, as discordance between radiographic and clinical severity indices is thought to be less with more severe grades of radiographic disease., Yet if we are to reduce the burden of functional disability due to knee OA, the role and contribution of each factor to disease burden will have to be well defined as it applies to different populations. This study aims to explore association between radiographic severity and functional disability in Nigerian knee OA patients.
| Materials and methods|| |
One hundred forty consenting knee OA patients were consecutively recruited between January 2010 and February 2011 as they presented to the Rheumatology Clinic of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, Nigeria. Knee OA was diagnosed in patients using American College of Rheumatology clinicoradiographic criteria. Sociodemographic and clinical information of patients was ascertained using a pretested interviewer-administered validated structured questionnaire. Patients had general examination and musculoskeletal examination with emphasis on the knees and anthropometric measurements. Functional disability was determined using Likert version of Western Ontario McMaster University (WOMAC) knee OA index. All patients had weight-bearing (standing) anteroposterior and lateral knee radiographs, with the index (most symptomatic) knee radiograph used in analysis.
All patients had weight-bearing (standing) anteroposterior and lateral radiography of the knees done and were interpreted and graded by a radiologist who was unaware of the information of the participants. Kellgren-Lawrence (K-L) criteria was used in grading the knee radiographs, with K-L score of at least grade 2 qualifying for radiographic disease. The K-L score used ratings from 0 to 4, where 0 = normal radiograph, 1 = doubtful pathology, 2 = minimal osteophytes, possible narrowing cysts and sclerosis, 3 = moderate disease, as evident by definite osteophytes with moderate joint space narrowing, and 4 = severe disease, with large osteophytes and definite joint space narrowing. The radiographs of the index (most symptomatic) knee was used for analysis. Based on the K-L rating, patients were categorized into two groups: those with mild radiographic disease (K-L grade 2) and those with severe radiographic changes (K-L grades 3 and 4).
Assessment of pain and functional disability using WOMAC OA index
The WOMAC OA index is a tridimensional, disease-specific, patient-administered health status measure. It probes clinically important, patient-relevant symptoms in the area of pain, stiffness, and physical function in patients with OA of the knee and/or hip. The index consists of 24 questions (5 on pain, 2 on stiffness, and 17 on physical functions) and can be completed in less than 5 minutes. It is the most widely used assessment tool and has become a standard measure for assessing patients with OA of the knee/hip. The WOMAC index has been validated in several researches and has a good test–retest reliability and responsiveness. It has the best clinimetric properties of all the assessment tools and is the most widely used., In the Likert version of WOMAC, patients rate the degree of pain, stiffness, and functional limitation experienced in the preceding 48 hours for each of the items using a five-level numeric descriptive scale (range = 0–4). Scores are generated for the dimensions of pain, stiffness, and physical function by summing the coded responses and then dividing by the number of items to provide a score range of 0 to 4 for each subscale. The activities included in the WOMAC physical function subscale are activities carried out commonly on daily basis and have face validity for lower limb functions.
All information was treated with utmost confidentiality, and data were analyzed using Statistical Package for Social Sciences, version 17 (SPSS Inc., Chicago, IL, USA).
Demographic and baseline characteristics were presented as tables. Univariate analyses were carried out and presented as range, mean [standard deviation (SD)] for numerical variables, and count/percentages for categorical variables. Correlation between knee radiographic severity and functional disability was determined using Spearman correlation coefficient. Linear regression analysis was done to determine the contribution of radiographic score to functional disability.
Ethical approval for this study was obtained from the research and ethics committee of ABUTH Zaria (ref. no.: ABUTH/PGO/COMM/9) and informed voluntary signed consent was sought and obtained from patients before their enrolment into the study.
| Results|| |
The baseline demographic characteristics of the 140 patients are shown in [Table 1]. One hundred twenty (85.7%) of the patients were female and 20 (14.3%) were male. The male:female ratio was 1:6.
|Table 1: Summary of the demographic characteristics of knee osteoarthritis patients (N = 140)|
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The mean ± SD age of the patients was 59 ± 8.8 years, with a range of 45 to 80 years. The mean ages for male and female patients were 61.3 ± 6.3 and 59.6 ± 8.8 years, respectively.
The frequency distribution of age groups of patients with knee OA is represented in. As a group, the patients were relatively fairly educated with a mean duration of 8.3 (±5.4) years of formal education. The occupational distribution of the patients is shown in [Table 1]. Of note is the low percentage of patients who are employed in labor-intensive, knee OA predisposing occupation like farming (7.1%).
None of the participants had past history of trauma to the knee, as those with significant past trauma to the knees were excluded from the study.
Analysis of knee pain and functional disability
All patients had knee pain during daily activities that necessitated their presentation at the rheumatology clinic, with mean ± SD duration of knee pain of 3.5 ± 2.9 years and a range of 4 weeks to 20 years. The various grades of pain severity in the patients studied is shown in [Table 2].
One hundred twenty (85.7%) patients had bilateral knee pain and 20 (14.3%) had unilateral knee pain. Ninety-eight (70%) patients reported that the right knee was the most symptomatic (index knee), whereas 42 patients (30%) noted that the left knee was the most symptomatic (index knee).
The mean ± SD disability score was 2.17 ± 0.89, range was 0 to 4, and median score was 2.21. Fifteen (10.7%) patients had no functional disability, 19 (13.6%) had mild functional disability, 81 (57.9%) had moderate disability, 21 (15%) had severe disability, and four (2.5%) had extreme disability. The various grades of functional disability in the patients studied is shown in [Table 2].
Analysis of K-L radiographic grade
All patients had definite knee OA on radiograph implying K-L score of at least 2 and above. The ranges of radiographic severity observed in the patients were as follows: grade 2 radiographic OA was seen in 51 (36.4%) patients, grade 3 in 71 (50.7%) patients, and grade 4 in 18 (12.9%) patients. Eighty-nine (63%) patients had severe radiographic OA (grade 3 or 4). Mean ± SD pain score was higher in patients with grade 3 or 4 radiographic score compared to grade 2 (K-L grade 3/4 vs. grade 2: 2.36 ± 0.78 vs. 1.83 ± 0.5; P = 0.000). Mean ± SD stiffness score was also higher in patients with radiographic scores of 3 or 4 compared with those with grade 2 (K-L grade 3/4 vs. grade 2: 1.20 ± 1.07 vs. 0.8 ± 0.8; P = 0.014). Mean ± SD disability scores was significantly higher among patients with grade 3 and 4 radiographic score compared to those with grade 2 (K-L grade 3/4 vs. grade 2: 2.44 ± 0.83 vs. 1.7 ± 0.82; P = 0.000). The frequency distribution of radiographic grades of the patients and the linear trend of increment of functional disability with increasing radiographic severity is shown in [Table 3].
|Table 3: Distribution of the grades of radiographic knee osteoarthritis in the patients and the linear trend between radiographic grade and mean pain, stiffness, and functional disability scores|
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There is a significant difference in mean pain score in patients with grades 2, 3, or 4 K-L radiographic score (F = 12.13, P = 0.000).
There is a significant difference in mean stiffness score in patients with K-L radiographic grades 2, 3, or 4 (F = 14.26, P = 0.000).
There is also a significant difference in mean functional disability score in patients with radiographic grades 2, 3, or 4 (F = 17.04, P = 0.000). Radiographic score correlated moderately with functional disability (rs = 0.48, P = 0.000) but showed weak positive correlation with mean stiffness score (rs = 0.28, P = 0.001) and mean pain score (rs = 0.36, P = 0.000).
Logistic regression analysis showed that K-L radiographic grades was an independent predictor of functional disability [Table 4].
| Discussion|| |
Knee OA is a public health problem given its high prevalence and associated functional disability. Determining factors that contribute to functional disability in a given population could be of help in further understanding the pathogenesis of the disease as well as enhance measures aimed at reducing disease-associated burden.
The sociodemographic profile of our study population are similar to those of earlier studies of Nigerian patients with knee OA,, the disease being more common among middle-aged females. The high prevalence of obesity in female patients and the higher health-seeking behavior of females compared to male patients could be contributory factors in the gender disparity seen in the prevalence of knee OA in this study. Predominance of women and the relative high level of education reduces the impact of occupation as a significant risk factor for development of knee OA in our study population. The prevalence of comorbidity was noted to be high in the study population, mostly consisting of obesity and hypertension. The high prevalence of comorbidity in knee OA patients have been well documented in the previous studies.,
Pain was the primary reason for presentation in all patients and was of moderate-to-severe intensity in the study population. Majority of the patients studied have moderate (23.6%) or severe pain (55.7%). The study population also have high prevalence of functional disability with majority having moderate (57.8%) or severe (15.0%) disability. Previous studies have alluded to the high prevalence of pain and functional disability in patients with knee OA., Knee OA is a significant contributor to global disability burden, and knee OA-induced disability is said to be as high as that of cardiovascular disease-induced disability, perhaps even higher than disability attributable to other medical conditions. Knee OA-induced functional disability also worsens disability associated with other medical conditions. Furthermore, the presence of knee OA can impede effective management approach in patients with other medical conditions, as it prevent exercise needed in the management of conditions like heart diseases, stroke, and obesity.
Of the several factors associated with knee OA, the effect size of radiographic severity on functional disability has been the most contentious. Research findings on the effect of radiographic severity on knee OA-induced functional disability has ranged from no impact in some studies, to moderate effect in other studies.,,
Our patients had severe radiographic disease at presentation implying stage 3 or 4 K-L grade, with a total of 63% having K-L grade 3 or 4 radiographic score at presentation. Mean pain and disability scores were noted to be higher in those with severe radiographic disease. Our findings are in agreement with researches that have pointed to higher pain and functional disability scores with advancing radiographic severity.,
Linear relationship was also noted between radiographic grades and clinical severity indices of pain and functional disability in our patients. Correlation between radiographic severity with both pain and functional disability have been alluded to by several studies.,, Multiple regression analysis confirmed that radiographic severity is an independent predictor of functional disability in our patients, thereby strengthening the association between the two variables. Radiographic grades have been shown to be an independent predictor of functional disability in several studies.,
Radiographic scores were more severe in those with obesity compared to those with normal body weight. Given that obesity is a known risk factor for progression of radiographic, and thus clinical knee OA, we advise that measures should be targeted at achieving ideal body weight in patients with knee OA, as weight reduction and optimization of BMI could have a dual benefit of reducing symptomatic knee OA as well as slowing or halting the progression of radiographic knee OA.
| Conclusion|| |
There is high prevalence of severe radiographic knee OA in Nigerian patients, with radiographic grade showing a moderate positive correlation with functional disability. Radiographic severity is an independent predictor of knee OA functional disability.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]