While the diagnosis of Pneumocystis carinii Pneumonia (yes – I know it’s changed it s name – but really, do you ask for Beanz when you want something tomatoey to go with your sausage, egg, black pudding, fried bread, mushrooms and juice in a morning?) may not be everyone’s weekly occurrence, there are probably a handful of children who are trying very hard not to develop in in your town.
The traditional approach to prophylaxis has been a spoonful of Septrin (TM), which got modifed to three times/week. Most of the UK leukaemia fraternity now moves with a twice/week, twice/day approach. But in Italy, there are centre which use a once-per-week schedule.
“On the basis of large RCT?” I hear you ask, knowing the great reputation paed onc has for developing research.
“Not .. quite..” comes back the embarrassed answer. “But there is some evidence …?”
A paper has recently popped up looking at the impact of dosing schedules on PCP prevention. This was a prospective one-year survey of centres, with their routine prophylaxis and routine diagnostic approaches, assessing the rates of PCP diagnosis. Some centres used 3/week, some 2/week, and three 1/week.
The most striking thing is that there were only two cases of PCP. And these turned out not to have taken their prophylaxis.
But the 1/week group – all 689 patients – there was not a single case.
Is this strong evidence for using 1/week? Well, it’s not randomised – so the group that got the 1/week might be systematically different than the others – but given it’s centre based not person based, this is likely to be influential if there is a marked geographical variation in PCP or in distribution of underlying malignancy (which is unlikely). Its not blinded; so there may be issues with patients presenting differentially, or being investigated differentially … but is it reasonable to assume that breathless patients on 1/week would be less likely to turn up than 2/ or 3/week? Or would the folk at centres differ in their approach to investigating ? (Well – that might be the case. There may well be a systematic difference in approach.)
Follow-up and change-in-approach (crossover) are pretty negligable in the guideline driven world that is paed onc.
Even if there is a systematic difference in investigation, that’s a ridiculously low rate of PCP. Is that in itself safe enough as 1/week, and make life easier for all our patients?
– Bob Phillips