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ARTHRITIS and HEALTH RISK

Note:  Arthritis is not included as a disease in Life Ahead Version #2.  It its risk from factors described following will be included in forthcoming Life Ahead Version #3

Arthritis Background:  Arthritis involves the reduction or destruction of cartilage that holds the bones of the body together, and keeps them apart.  Deficient cartilage often causes pain at the knee, hip, back, and /or hand that can become severe. Osteoarthritis is by far the most usual type of arthritis that afflicts the majority of sufferers as they move well past middle age.  Rheumatoid arthritis that afflicts only 10-15% as many individuals is a somewhat different and more serious type that can afflict younger people. Other less usual forms include gout.  Life Ahead identifies principally the factors that  increase the incidence of - or risk of getting a disease - that needs action by individuals.  A companion need is for treatment of those that already have the disease, the role of the doctor. A large majority of both research and discussion about arthritis refers to treatment options, and not about its risk of occurrence.  Except for use of proper exercise and avoiding overweight, little seems to have been learned about other ways for stopping the occurrence of arthritis. 

A substantial fraction of all older adults become afflicted with one or more forms of arthritis.  Estimates of the percentage of men and women that are afflicted with some kind of arthritis at age is noted in the table opposite.:

A large percentage of all women become afflicted with some type of arthritis as they move past age 60. Specific levels of the disease range from uncomfortable pain in one more more body joints to severely crippling levels that can  require serious  hip or knee surgery. The figures opposite approximate US self reported events of white people for all types or arthritis and types that involve some disability. Rates identified in Life Ahead are for partly disabling levels of arthritis, and these can be only a third to a fifth or less of all persons that suffer some form of the disease.

Women have about one and one half  times the risk of men, and blacks can have one and one half times the risk of whites.  After age 70 a third or more of all women usually become afflicted.  Most serious osteoarthritis occurs at the hip or knee. The continual pain of arthritis can significantly diminish the quality of life.  Death rates are rarely attributed directly to arthritis per se. But disabling arthritis can limit exercise and help cause overweight that can result in substantially increased death rates from heart disease and other major causes.  At least one study found a 40% higher overall death rates for individuals that suffered disabling arthritis.

The Risk Factors:  As above, a discouraging problem with arthritis is the small number of actionable lifestyle factors that are involved in its risk.  Most major health problems are substantially affected by multiple factors that individuals themselves can control.  But most of these usual risks including that of diet do not appear confirmed to reduce the risk of suffering arthritis.

The table following includes most of the key research found published that pertain to risks of suffering arthritis. As will follow, the only lifestyle factor that is solidly confirmed as a large risk is body weight in BMI. Also, correct and incorrect types of physical activity and exercise can decrease or increase risk. There is much commentary about risks of arthritis in the press and in various health advice that is not based on adequate research.  The results of the actual  research found on various factors follows.

Smoking:  A number of small earlier studies found smoking not only to have no effect on incidence of arthritis but as for study A1 in the following Table A, some suggested that smokers suffered less arthritis. Actually, very little good research on smoking and arthritis appears to have been done. Study A2 found no effect of smoking, and A3 and A4 found smoking to be harmful  But A3 was for much smaller group having rheumatoid arthritis and A4 was too small to be of much significance.  The research here is insufficient to identify a useful effect of smoking on this disease. Smoking and especially of cigarettes is solidly confirmed as increasing risk of most other major disease.  Thus stopping it provides a major contribution to length and quality of life.  But Life Ahead now acknowledges no effect of smoking on risk of arthritis based on the scanty evidence available.

Exercise and Cardiofitness:  Eight studies B1 through B8 in the following Table A relate exercise to risk of osteoarthritis. Results appear superficially inconsistent.  But on more detailed analysis they do infer a fairly consistent picture. Physical activity works in two different ways. Any injury of a vital body joint as the knee developed during exercise greatly increases the development of arthritis there at a later age. Study B6 shows this with a very high risk of 8 times normal for arthritis at sites that suffered earlier injury.  Physical activity during occupation was generally harmful as per studies B1 B2 and B3. Such activity often involved heavy lifting and other stress on the body but rather small effective aerobic type exercise.  Study B4 also found that young men that ran more than 20 miles per week suffered a higher risk, but no effect was found for older persons running. A possible reason for this is that younger people probable ran more vigorously with more stress on knees than did those older.  And 20 and more miles per week is a regime more stressful than that needed for healthful improvements in cardiofitness.  Study B3 noted added risk for a combination of those doing heavy physical activity and that also had high body weight in BMI.

Although such types of stressful physical activity can promote arthritis, the larger studies B5, B7, and B8 each show that the usual leisure time type of exercise that improves cardiofitness reduces risk of arthritis. Study B5 found that men obtained reductions in risk of nearly 4 times by exercise the should have improved CFR substantially. Women had about 40% lower risk of what probably was lesser exercise.  Study B7 from Finland found those that participated in most sports obtained a half to two thirds reduction in usual risk.  The exception here was those participating in team sports that did not obtain benefit.  Team sports would involved far more body contact and potential joint injury than would occur in individual exercise.  Study B8 also found a 30% reduction in arthritis for those doing the most exercise. No useful research results were found for resistance type exercise.

This research supports the previous observation that exercise can work in two ways.  First, the activity the places undue stress on key joints as the knee or hip can cause injury the promotes later life arthritis. But regular moderate exercise of joints is beneficial.  In other words, body joints need to be continually used, but not injured.  Interestingly, even the running in studies B5 and B7 was very beneficial.  Much of the occupational activity that in the past involved the physical stress and that would increase risk of arthritis now has been replaced with use of machinery. Thus it is unlikely that today's usual occupational physical activity would promote much arthritis.

Health-interested persons that will benefit from using Life Ahead should be doing regular aerobic exercise.  This type of exercise, or any exercise that keeps the body moving as for example even Tai Chi should reduce risk of arthritis.  Excessive exercise that substantially stresses the knees or hips should be avoided.  Life Ahead includes an estimated benefit for cardiofitness as noted opposite based on results of B5, B7, and B8, but acknowledges a maximum benefit for a CFR improvement of only 15 units above average. 

An important assumption in this relation is that CFR be obtained via exercise that does not injure key body joints.  In summary, the logical key to beneficial exercise is:  Exercise regularly and aerobically, and and keep all parts of the body moving.  But avoid excessive stress that might injure your body and its joints.

Body Weight and the BMI:  The results of 6 studies, D1 through D6 in the Table A following each confirm a substantial effect of body weight on arthritis. Most of these studies identified the risk of arthritis of the knee or of disability from arthritis that are the more serious consequences of this disease.  The implication here is that increased weight place more stress on the joints that support body weight and are the keys to disability.  This in turn increased the incidence of arthritis.  The table following shows results of an analysis of results of all of these studies:

The effect of BMI on arthritis is moderate for the usual healthy range of 22 to 26.  But risk moves up 71% higher at a BMI of 30, to more than twice higher at a BMI of 34, and to more than 4 times higher for those quite obese. A curious problem here is that the risk of knee and hip disability also can be caused by osteoporosis. And the effect of overweight on osteoporosis is beneficial.  Yet this benefit for osteoporosis appears cancelled out by the negative benefit of overweight for risk of arthritis, and reversed into a serious overall risk for overweight. The effect of BMI noted in the table opposite is an average from all six studies. But the effect of BMI found in these studies varied substantially. 

Studies D1 and D2 for knee arthritis show far higher risks than do the other more general studies. Study D2 of 525 patients listed for knee surgery noted a range in risk of more than 100 to 1 for BMI of about 36 vs. a lowest BMI of about 18.  This suggests a strikingly large effect of body weight on need for knee surgery because of severe arthritis. Thus being overweight not only increases risk of the major cardiovascular diseases and cancer but also substantially increases risks of getting diabetes or related nephritis, dementia, and potentially disabling arthritis.

Arthritis is not included in Life Ahead as a separate risk of death, and only its expected likelihood as a disease is shown.  But the risk of BMI for arthritis that is harmful is closely associated with the risk of BMI from osteoporosis that is beneficial. Because osteoporosis is included as a life terminating factor and arthritis is not, a sum total risk of BMI on the two diseases is computed as a death determining  factor.  Because the risk of arthritis is far greater than the risk of osteoporosis, the net effect of increased BMI or body overweight on these diseases is very harmful.

Diet and Vitamins:  No useful research was found relating risk of osteoarthritis development to diet.  Statements were found claiming that "Risk may be reduced by fruits and vegetables and omega-3 fats, and increased by meat."  But no results confirming this for arthritis were noted in studies C1, C2 and C3 found. 

Study C1 on a small group in the Framingham study did claim an advantage for the popular antioxidant vitamins.  Clinical study C3 found no such effect for 500 mg of Vitamin E. The largest study, also from Framingham found no effect of diet, and no effect of Vitamin D measured either in diet or of amounts in blood on incidence of or severity of osteoarthritis.  This research is too limited to deny that useful effects of diet and diet supplements on the incidence of arthritis might exist.  But at this writing no effect of these usually important factors can be ascribed to this with any validity.   

Replacement of Female Hormones:  There has been much discussion of and claims that replacement of female postmenopausal hormones will reduce the risk of arthritis.  The five studies of this, E1 through E5 in the Table A following. provide no confirmation that this is true.  Study E1 does show a significant benefit.  But studies E3, D4, and D5 show no effect of hormone use on osteoarthritis, and study E2 does not reach usual significance. There are many variables here that are not defined.  For example, differences in type and source of hormone used, length of time of the studies, amounts of hormone, etc. Thus there might be a combination here that as in Study C1 could provide a benefit.  But at this writing, no effect of hormone use can be validated for use in Life Ahead.

TREATMENT of OSTEOARTHRITIS:  Treatment of disease is not included in Life Ahead.  But glucosamine and chondroitin are supplements available without prescription that have their benefits confirmed from more than adequate research.  These can reduce the pain and progress of osteoarthritis for many and probably will do the same for rheumatoid arthritis. Thus this research is noted here.  No effect of these supplements on risk of getting the disease was found, and their benefit is not now included in Life Ahead.  But it seems likely from chemistry involved that they probably will reduce risk of the disease somewhat for those concerned.  At least 37 studies of these popular supplements have been published, and they have been used extensively by the public for more than 20 years.

Results from a selected best 15 of these studies were analyzed in a Meta analysis noted as F1 in the following Table A. Despite the substantial conservatism of the study authors, it was noted that every study found a benefit in reduced pain and progression.  And that average benefit for glucosamine was assessed as "Moderate Effect" and that for chondroitin was assessed as nearly  "Large Effect".  Missing in the analysis was any assessment of amounts of these supplements needed.  But an average amount of glucosamine studied was about 500 mg/day, and of chondroitin, 1000 mg/day. These average different amounts might explain the better assessments given to chondroitin.  But no advantage in the research was noted for amounts of glucosamine higher than 500 mg/day. Study F2 on pain only that was larger than most of those in F1 cited "No significant reduction in Pain" for the regimes tested.  But a closer look at the study shows small improvement for those taking either glucosamine or chondroitin sulfate individually, and a near significant improvement of 6.5% for combined therapy. Although small, it should be recognized that a measurement of pain is very difficult and there always can be a substantial placebo effect in these randomized studies that can partly mask a true effect.  On balance, the overall results of 16 studies support some benefit for these supplements.

A common regime promoted for these supplements is a three pill per day total of 1500 mg of glucosamine and 1200 mg of chondroitin.  This appears to be an overkill in amount when compared to the actual research amounts studied and these supplements can be moderately expensive.  A combination of the two supplements totaling 1500 mg/day should  be more than sufficient to provide the maximum verified potential benefit.  Perhaps even one of these pills per day would be sufficient.  Although there are few side effects of these supplements, it has been that suggested they be avoided by pregnant women and by those allergic to shellfish.  And a doctor's advice could be useful, particularly if other medications are being taken. Another nutrient called MSM is sometimes included and touted in these supplements.  But no useful research now confirms a benefit for this MSM.