I presume you ask because the diagnostic criteria appear to make a six week history mandatory. I was not a trained paediatric rheumatologist, but prior to 1985 I saw children as part of general rheumatological practice and then worked exclusively on adult inflammatory arthritis. However, I think the diagnostic principles must be the same.

Diagnostic criteria are designed partly for research purposes and partly to standardise and validate indications for major drugs like biologics. I do not think they ever provide a rule for clinical practice. If a patient has all the signs of an inflammatory arthritis for even a week then the diagnosis is at least part of a differential and by a month it can be a reasonable working certainty if other differentials have been excluded. Excluding infection is clearly the salient issue. Other differentials like post-infective syndromes and rarities like Wilson's disease may also be important but I do not think there is anything magic about 6 weeks there. What I would consider important is that if you think there is a strong indication for major anti-inflammatory therapy - steroid or biologic or whatever that it may be reasonable to think that delay may do more harm than an inaccurate diagnosis. The stipulation of 6 weeks is likely to reflect expert opinion on the balance of risks and the problems of exposing a young child to toxic therapy inappropriately but it will only be a guide. Joints can be destroyed in 6 weeks so I do not think it can be an absolute. 

So from my adult practice perspective I would say yes you can make a provisional diagnosis of JIA. How you handle that in terms of therapy must be a matter of clinical judgment, which as ever has to use whatever evidence you can muster - always less than perfect. JIA is not an easy thing to assess and few physicians see enough to know all the pitfalls. Another paediatric opinion would be valuable but sometimes one has to have faith in ones assessment. 

Thank you Jonathan sir for your elaborate explanations. It is clear to me now.

Dear Shubhankar

I agree with Dr Edwards...

The duration of arthritis for diagnosis is set at SIX weeks essentially to rule out  infective and post infective (reactive) arthritis. 

One can definitely make a diagnosis of JIA before 6 weeks - in the instance of systemic onset JIA where the diagnostic criteria mentions only 2 weeks of daily temperature spikes (not 6 weeks).

In other subtypes of JIA, one may be able to diagnose earlier (4-5 wks) in some instances going by factors like the pattern of arthritis or associations - for example, if you have extensive polyarthritis affecting multiple small joints or when there is associated psoriasis, in which cases any other pathology is less likely. We have started definitive therapy by 4-5 weeks in some such scenarios. In any case they could be commenced on a rheumatological dose of NSAIDs at the first review which should afford some relief.

The problem most often arises in oligoarthritis affecting large joints especially monoarthritis, in which case waiting for six weeks is unlikely to cause long term damage of joints. They too should be commenced on NSAIDs at the earliest.

In most situations, this period could be used for investigations to rule out alternate pathology like ASO titre, Lyme serology etc, as indicated.

Regards

Kishore.

Kishore sir thanks for answering my query. I am now clear about the clinical scenerio.

1. Yes it is possible to diagnose JIA before 6 consecutive weeks of arthritis observed by a physician. It is possible in case of flagrant symmetrical poly-arthritis resembling the adult type.

2. It is more difficult in monoarthritis (rule out infection or tuberculosis).

3. The rule of 6 weeks was established at first to rule out migratory arthritis where inflammation does not stay in a given joint more than 2-3 weeks (usually much less especially with treatment) and in all the joints 4-6 weeks.

4. NSAIDs can be started as early as possible before the 6 weeks time. A quick and remarkable response would plead against JIA and is usually seen in rheumatic fever, where the response in a given joint appears within days.

In case of strong index of suspicion of JIA, even hydroxy-chloroquine  can be started early. DMARDS can wait 6 weeks but not more for fear of rapid damage.

5. I am not sure what you mean by “evolving” JIA. If you mean rapidly progressing, it does exist and there is no way to predict from the outset who is going to deteriorate quickly. Early hip or wrist involvement, symmetrical disease, the presence of RF predict bad long term outcome.