https://www.rheumatic.theclinics.com/article/S0889-857X(08)00041-0/pdf

Epidemiology of Osteoarthritis

Osteoarthritis (OA) is a leading cause of disability and its incidence is rising due to increasing obesity and an ageing population. Risk factors can be divided into person-level factors, such as age, sex, obesity, genetics, race/ethnicity and diet, and joint-level factors including injury, malalignment and abnormal loading of the joints. The interaction of these risk factors is complex and provides a challenge to the managing physician. The purpose of this review is to illustrate how each of these factors interact together to instigate incident OA as well as to outline the need for ongoing epidemiologic studies for the future prevention of both incident and progressive OA. It is only by understanding the impact of this disease and the modifiable risk factors that we will be able to truly target public health prevention interventions appropriately.

The epidemiology of osteoarthritis

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

/pdf/the-rotterdam-study-objectives-and-design-update-2n3pqovgsq.pdf

The Rotterdam Study: Objectives and design update

Risk factors for onset of osteoarthritis of the knee in older adults: a systematic review and meta-analysis.

Obesity is associated with a number of medical conditions that lead to increased morbidity and increased mortality. Both the National Institutes of Health and the World Health Organization define obesity as a body mass index (BMI) > or = 30 kg/m2 and overweight as a BMI 25-30. The most common conditions associated with obesity are insulin resistance, diabetes mellitus, hypertension, dyslipidemia, cardiovascular disease, gallstones and cholecystitis, sleep apnea and other respiratory dysfunction, and the increased incidence of certain cancers. These are discussed below.

The Medical Risks of Obesity

Objective. Although knee malalignment is assumed to correlate with knee osteoarthritis (OA), it is still unknown whether malalignment precedes the development of OA or whether it is a result of OA. The aim of this study was to assess the relationship between malalignment and the development of knee OA as well as progression of knee OA. Methods. A total of 1,501 participants in the Rotterdam study were randomly selected. Knee OA at baseline and at followup (mean followup 6.6 years) was scored according to the Kellgren/Lawrence (K/L) grading system. Alignment was measured by the femorotibial angle on radiographs at baseline. Multivariable logistic regression for repeated measurements was used to analyze the association of malalignment with the development and progression of OA. Results. Of 2,664 knees, 1,012 (38%) were considered to have normal alignment, 693 (26%) had varus alignment, and 959 (36%) had valgus alignment. A comparison of valgus alignment and normal alignment showed that valgus alignment was associated with a borderline significant increase in development of knee OA (odds ratio [OR] 1.54, 95% confidence interval [95% CI] 0.97-2.44), and varus alignment was associated with a 2-fold increased risk (OR 2.06, 95% CI 1.28-3.32). Stratification for body mass index showed that this increased risk was especially seen in overweight and obese individuals but not in non-overweight persons. The risk of OA progression was also significantly increased in the group with varus alignment compared with the group with normal alignment (OR 2.90, 95% CI 1.07-7.88). Conclusion. An increasing degree of varus alignment is associated not only with progression of knee OA but also with development of knee OA. However, this association seems particularly applicable to overweight and obese persons.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.22515

Association between valgus and varus alignment and the development and progression of radiographic osteoarthritis of the knee.

Objective: To investigate the relationship between body mass index (BMI) and the incidence and progression of radiological knee as well as of radiological hip osteoarthritis. Design: Cohort study. Setting: Population based. Participants: 3585 people aged ⩾55 years were selected from the Rotterdam Study, on the basis of the availability of radiographs of baseline and follow-up. Main outcome measures: Incidence of knee or hip osteoarthritis was defined as minimally grade 2 at follow-up and grade 0 or 1 at baseline. The progression of osteoarthritis was defined as a decrease in joint space width. Methods: x Rays of the knee and hip at baseline and follow-up (mean follow-up of 6.6 years) were evaluated. BMI was measured at baseline. Results: A high BMI (>27 kg/m 2 ) at baseline was associated with incident knee osteoarthritis (odds ratio (OR) 3.3), but not with incident hip osteoarthritis. A high BMI was also associated with progression of knee osteoarthritis (OR 3.2). For the hip, a significant association between progression of osteoarthritis and BMI was not found. Conclusion: On the basis of these results, we conclude that BMI is associated with the incidence and progression of knee osteoarthritis. Furthermore, it seems that BMI is not associated with the incidence and progression of hip osteoarthritis.

https://ard.bmj.com/content/annrheumdis/66/2/158.full.pdf

Body mass index associated with onset and progression of osteoarthritis of the knee but not of the hip. The Rotterdam Study

Objective. To provide an overview of prognostic factors of knee osteoarthritis (OA) progression. Methods. We searched Medline and Embase up to December 2003 according to a specified search strategy (keywords for disease, location, and study design). Studies that fulfilled predefined criteria were assessed for methodologic quality. Study characteristics and associations were extracted and the results were summarized according to a best evidence synthesis. Results. Of the 1,004 studies found, 37 met the inclusion criteria. Methodologic quality was assessed and only high-quality studies were included (n = 36). The best evidence synthesis yielded strong evidence that hyaluronic acid serum levels and generalized OA are predictive for progression of knee OA. Sex, knee pain, radiologic severity, knee injury, quadriceps strength, and regular sport activities were not predictive. Conflicting evidence for associations was found for several factors including body mass index and age. Limited evidence for an association with progression of knee OA was found for several factors, including the alignment (varus/valgus) of the joint. Limited evidence for no association with progression of OA was also found for several factors, including meniscectomy, several markers of bone or cartilage turnover, and the clinical diagnosis of localized OA. Conclusion. Generalized OA and level of hyaluronic acid seem to be associated with the radiologic progression of knee OA. Knee pain, radiologic severity at baseline, sex, quadriceps strength, knee injury, and regular sport activities seem not to be related. For other factors, the evidence was limited or conflicting.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.22475

Prognostic factors of progression of osteoarthritis of the knee: a systematic review of observational studies.

OBJECTIVE\nTo predict the 1-year outcome of incident nontraumatic knee symptoms in adults presenting in general practice.\n\n\nMETHODS\nAdults age >35 years with nontraumatic knee symptoms (n = 480) were followed for 1 year. At baseline, data on knee symptoms and demographics were collected and a physical examination performed. Knee symptoms were assessed by self-report questionnaires at 3-month intervals. After 1 year the physical examination was repeated. Multivariate prognostic regression models of patient characteristics, symptom characteristics, and physical examination were used to predict persisting knee symptoms after 1 year. Areas under receiving operating characteristic curves (AUCs) were used to determine the predictive value of the model. To assess the added predictive value of symptom characteristics and physical examination, these models were added to the model of patient characteristics. The improvement was expressed as the difference between the 2 AUCs.\n\n\nRESULTS\nIn the multivariate prognostic model of patient characteristics, age >60 years, educational level, kinesophobia, and comorbidity of the skeletal system were associated with persistent knee symptoms after 1 year (AUC 0.67). Of the symptom characteristics, history of nontraumatic knee symptoms, bilateral symptoms, and duration of symptoms >3 months were associated (AUC 0.73). For determinants of physical examination, crepitus of passive extension was associated (AUC 0.55). The added value of the symptom characteristics model to the patient characteristics model was 0.09 (AUC 0.76). Physical examination added no further value.\n\n\nCONCLUSION\nSymptom characteristics are the strongest predictors of persisting knee symptoms at 1-year followup. Physical examination has no added value in predicting persistent knee symptoms in general practice.

Prognostic factors in adults with knee pain in general practice. The HONEUR knee cohort

Objective

To predict the 1-year outcome of incident nontraumatic knee symptoms in adults presenting in general practice



Methods

Adults age >35 years with nontraumatic knee symptoms (n = 480) were followed for 1 year At baseline, data on knee symptoms and demographics were collected and a physical examination performed Knee symptoms were assessed by self-report questionnaires at 3-month intervals After 1 year the physical examination was repeated Multivariate prognostic regression models of patient characteristics, symptom characteristics, and physical examination were used to predict persisting knee symptoms after 1 year Areas under receiving operating characteristic curves (AUCs) were used to determine the predictive value of the model To assess the added predictive value of symptom characteristics and physical examination, these models were added to the model of patient characteristics The improvement was expressed as the difference between the 2 AUCs



Results

In the multivariate prognostic model of patient characteristics, age >60 years, educational level, kinesophobia, and comorbidity of the skeletal system were associated with persistent knee symptoms after 1 year (AUC 067) Of the symptom characteristics, history of nontraumatic knee symptoms, bilateral symptoms, and duration of symptoms >3 months were associated (AUC 073) For determinants of physical examination, crepitus of passive extension was associated (AUC 055) The added value of the symptom characteristics model to the patient characteristics model was 009 (AUC 076) Physical examination added no further value



Conclusion

Symptom characteristics are the strongest predictors of persisting knee symptoms at 1-year followup Physical examination has no added value in predicting persistent knee symptoms in general practice

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.24419

J. N. Belo

Papers

Association between valgus and varus alignment and the development and progression of radiographic osteoarthritis of the knee.

Body mass index associated with onset and progression of osteoarthritis of the knee but not of the hip. The Rotterdam Study

Prognostic factors of progression of osteoarthritis of the knee: a systematic review of observational studies.

Prognostic factors in adults with knee pain in general practice. The HONEUR knee cohort

Prognostic factors in adults with knee pain in general practice