Glucosamine and Chondroitin (Combination)

This is a strong recommendation resting on an absence of benefit rather than on demonstrated harm, and the guideline notes glucosamine's toxicity is low. It hardened from a conditional recommendation against glucosamine in 2012, so a reader may still meet the older advice. The search closed in 2018.

None was designed to detect rare harm, and the participants were people with knee osteoarthritis, not the general population. The chondroitin review's finding of fewer serious events on treatment than on placebo more likely reflects sparse, inconsistently reported data than a real effect.

The 0.9 cm threshold is these authors' own choice rather than an agreed one, and a reader accepting a smaller threshold would read some of these intervals differently. Restricting by trial size excludes most of the older positive literature, so this is not the body of trials other reviews pool.

A placebo response of six in ten leaves very little room for a supplement to show a difference, and every arm could take up to 4,000 mg of paracetamol a day as rescue, narrowing the gaps further. The trial used glucosamine hydrochloride, not the sulfate salt sold in Europe as a medicine.

This is a continuation in the participants who met stricter X-ray criteria, not a fresh randomisation, so it carries the parent trial's high placebo response with it. Two years of dropout leaves less power, not more. The authors call the trends beneficial but not significant, which describes a null.

The result is fragile: its interval reaches to 0.002 mm, its p value is 0.046, and it survives only after adjustment for sex, weight and baseline severity. It is one of several comparisons, so a multiple-testing correction would likely remove it. Whether a tenth of a millimetre is felt is untested.

The subgroup was one of two specified in advance, but was never powered as a test of its own and no independent trial has repeated it. The Spanish trial is small, at 164 people, and its placebo group's larger improvement appears only when everyone randomised is counted, vanishing among completers.

Milder knees showed a trend toward benefit with no significance test attached to it, so it is not a result and should not be reported as one. The trial used glucosamine hydrochloride rather than the sulfate salt, which is one of the two ways it differs from the three-year trials reporting a benefit.

This is one manufacturer's label, so its choices are evidence about this product rather than about US labelling rules in general. The document also disagrees with itself: the index title says tablet where the Drug Facts panel and carton say capsule, and three different effective dates appear in it.

The bar for counting as no worse was 40 points on a 0-to-500 pain scale, which is wide. The pair used glucosamine hydrochloride, the salt an earlier analysis concluded was ineffective, which makes matching a prescription drug harder to square with the rest of this literature rather than easier.

This review does not separate trials by manufacturer, by funder, or by how well allocation was concealed, the three things earlier analyses of this literature found decide the answer. Its combination conclusion rests on three trials. It reports direction and significance, no effect sizes.

Whether chondroitin and glucosamine ease pain turns on method, not data. Analyses splitting trials by funder, brand and trial quality find no difference a patient would notice; the review finding a benefit did not split them.