Smoking and diabetes are protective factors for osteoarthritis | APLAR 2021

*It is only for medical professionals to read for reference.
Although studies have shown that smokers are less likely to develop severe osteoarthritis, it is recommended that everyone stay away from tobacco! At the 2021 Asia-Pacific Association of Rheumatology Association (APLAR) Annual Meeting held in Kyoto, Japan, Professor Katy Ying Ying Leung from Singapore General Hospital shared the latest developments on the risk factors of osteoarthritis (OA)
.

There is a huge unmet need in the OA field.
OA is a very complex disease with slow progress and is related to genetics, life>
.

Knee osteoarthritis (KOA), a type of OA, has a high incidence and is one of the main causes of pain and disability, leading to decreased productivity and a large amount of medical insurance expenditures
.

KOA is also the cause of 97% of total knee arthroplasty (TKR)
.

However, there is currently no effective treatment for KOA, and none of the drugs has been proven to slow the progression of the disease
.

Its specific etiology and pathogenesis are still unknown, but it is speculated that inflammation may play a key role in it
.

Risk factors and protective factors of KOA The Singapore Chinese Health Study (SCHS) is a good database for studying KOA
.

This is a population-based prospective cohort study.
Between 1993 and 1998, 63257 cases of Chinese aged 45 to 74 were enrolled
.

The research investigated items such as demographic data, life>
.

As of December 2019, 2816 subjects had undergone TKR surgery due to KOA
.

The SCHS study has several major advantages.
First, the sample size is large, with a total of 63,000 subjects included; second, the loss to follow-up rate is low, only 0.
07%; the database is rich, including demographic data, life>
.

According to SCHS, risk factors for TKR in KOA patients include BMI, physical activity> 5h/w, gout, and more children.
TKR is negatively related to smoking, diabetes, and the consumption of legumes.
Dietary fiber intake is a neutral factor
.

According to SCHS, BMI is positively correlated with KOA.
It can be seen that the higher the BMI, the greater the risk of KOA (Figure 1)
.

Figure 1 The relationship between BMI and KOA risk.
The same conclusion can be observed from Table 1.
For both men and women, the greater the BMI, the higher the probability of TKR (Table 1)
.

Table 1 Relationship between BMI and TKR According to SCHS, when physical activity is performed for 0.
5 to 2 hours a week, the risk of TKR is small; too little or too much physical activity will increase the risk of TKR (Table 2); the more sleep a day, the lower the risk of TKR
.

Table 2 The relationship between physical activity and TKR In SCHS, there is basically no difference in BMI for never-smokers, ex-smokers, and current smokers
.

Surprisingly, smoking actually reduces the risk of TKR.
Never-smokers have the highest TKR risk, while those who quit smoking are slightly lower.
Current smokers can reduce the TKR risk by 51%; the more smokers and the longer they smoke, the lower the TKR risk.
(Table 3)
.

Table 3 The relationship between smoking and TKR SCHS also studied the relationship between fertility factors and TKR, and concluded that the greater the number of children, the greater the risk
.

The principle may be related to the influence of hormones and the mechanical load caused by holding a child (Table 4)
.

Table 4 The relationship between fertility and TKR SCHS also found that contrary to common sense, the relationship between diabetes and TKR is also negatively correlated.
Using three different models, a unified conclusion is reached.
Diabetes patients have a lower risk of TKR than those without diabetes, which can be reduced.
More than 30% (Table 5)
.

Table 5 The relationship between diabetes and TKR A meta-analysis involving 31 studies and 295,100 samples also pointed out that diabetes is not a risk factor for OA; BMI is still the biggest confounding factor
.

The SCHS study also concluded that legume intake can help reduce the risk of TKR, but dietary fiber (including dietary fiber in grains, nuts, soy products, fruits and vegetables) has little to do with TKR
.

Gout is a major risk factor for severe KOA.
The incidence of KOA in people with gout is 20% higher than that in people without gout; especially in thin women, the impact of gout is greater, and the risk of KOA can be increased by 117% (Table 6)
.

Table 6 The relationship between gout and KOA.
Anti-inflammatory is a possible effective treatment strategy for OA.
What role does inflammation play in the pathogenesis of OA? It can be seen that OA has typical inflammatory characteristics, such as redness, swelling, heat, and pain
.

Colchicine can act on OA through multiple mechanisms
.

Professor Leung’s team hypothesized that colchicine might block the inflammatory response mediated by inflammasomes, thereby improving the symptoms and signs of OA, and conducted a single-center double-blind randomized controlled trial
.

The test result was negative.
Compared with placebo, colchicine did not significantly improve the short-term symptoms of KOA, but it reduced inflammation and reduced bone turnover markers
.

Studies have shown that the pro-inflammatory cytokines in synovial fluid (such as IL-1β, IL-6, TNF-α, etc.
) are related to pain after activity, rather than resting pain; inflammatory biomarkers are moderately related to the severity of KOA
.

Some progress has also been made in research related to anti-cytokine therapy.
For example, adalimumab can improve interphalangeal joint erosion and swelling in patients with erosive hand OA
.

Summary: According to SCHS, the risk factors of TKR include excessive BMI, physical activity> 5h/w, gout, and excessive number of children; the protective factors of TKR include smoking, diabetes and legume intake; dietary fiber is a neutral factor
.

Regarding the improvement of KOA treatment, future research perspectives can include weight loss, prevention of weight gain, muscle gain exercise, biomechanical intervention, and so on
.

Experts comment that OA is the most common chronic bone and joint disease in the world.
It mainly affects weight-bearing joints such as knees and hips.
It is characterized by cartilage degeneration on the articular surface and bone hyperplasia at the joint edges.
It is one of the main disabling diseases
.

The prevalence of OA in China is more than 10%, and it is showing a rising trend with the aging of the population and changes in life>
.

Due to the lack of fundamentally effective treatments for OA, it is important to understand how to prevent the occurrence and development of the disease
.

This study used SCHS as the data source to analyze the risk factors of TKR in KOA patients
.

Studies have shown that high BMI, long hours of physical labor, combined with gout, and a large number of children are risk factors for TKR
.

Contrary to the results of previous studies and general cognition, the study found that smoking and diabetes are associated with a decrease in the incidence of TKR, which may be related to the presence of confounding factors such as BMI or other collinearity factors
.

The author finally summarized the new developments in KOA treatment, including the efficacy of anti-cytokine therapy in rheumatoid arthritis in patients with OA
.

 Expert Profile Chen Zhu, Deputy Chief Physician, Deputy Chief Physician, Department of Rheumatology and Immunology, First Affiliated Hospital of University of Science and Technology of China, Chief Assistant, Specially Appointed Researcher, University of Science and Technology of China, Doctoral Supervisor, Doctor of Medicine, University of Erlangen-Nuremberg, Germany, Cornell University, USA Postdoctoral Fellow of the Hospital of Surgery, Anhui Province Academic and Technical Leader, and Reserve candidate