{"id":635,"date":"2009-04-01T13:37:39","date_gmt":"2009-04-01T12:37:39","guid":{"rendered":"https:\/\/stg-blogs.bmj.com\/bmj\/?p=635"},"modified":"2009-04-01T16:11:33","modified_gmt":"2009-04-01T15:11:33","slug":"nice-and-the-influenza-antivirals-for-healthy-adults-no-again-and-again-and-again","status":"publish","type":"post","link":"https:\/\/stg-blogs.bmj.com\/bmj\/2009\/04\/01\/nice-and-the-influenza-antivirals-for-healthy-adults-no-again-and-again-and-again\/","title":{"rendered":"NICE and the influenza antivirals for healthy adults – No, again and again and again"},"content":{"rendered":"

NICE\u2019s\u00a0 latest technology appraisal of the\u00a0 flu antiviral drugs<\/a> (amantadine, oseltamivir and zanamivir), published in February 2009\u00a0 marks the sixth time these drugs have been considered. The timelines are\u00a0 shown below.<\/p>\n

In brief NICE has taken and maintained a strong position against the use of these drugs except for tightly defined at risk groups. What\u00a0 interests me is the arguments that have been used to show that these drugs are not cost effective treatments\u00a0 for healthy people. These arguments I think hinge on assumptions which largely lack evidence.<\/p>\n

The cost per QALY (or QADay) calculation are fairly simple as follows, with\u00a0 figures I have taken from the most recent\u00a0 NICE appraisal. Both zanamivir and oseltamivir cost around \u00a316. On average and taken within 48 hours of symptom onset, when influenza virus A or B is circulating, they reduce the\u00a0 number of days before return to normal activities\u00a0 by around 1. If the QALY loss due to having symptoms is 0.5, the cost per QALY would be \u00a332 (16\/0.5). Factor in the probability of 0.5 that symptoms are not flu and the cost per QALY doubles to \u00a364.(16\/0.5\/0.5) Compare this with NICEs \u00a320k\/QALY threshold (=\u00a355 per QADay) rising to \u00a382 per QADay at the \u00a330k threshold. This\u00a0 crude calculation puts these drugs between\u00a0 NICE\u2019s upper and lower thresholds. This is why two other considerations mattered, one which reduces,\u00a0 the other which increases,\u00a0 the cost per QADay.<\/p>\n

If one assumes that successful treatment with an antiviral\u00a0 averts deaths (such as post influenza pneumonia) and associated hospitalisations, then the QADays would be increased and the cost\u00a0 reduced. Although the number of deaths is unknown and\u00a0 might well be small, the effect could be considerable. The cost per QALY for zanamivir for healthy adults fell from \u00a330k to \u00a38k when hospital admissions and deaths were included in NICE\u2019s 2003 appraisal<\/a>.<\/p>\n

Against this the Appraisal Committee worried about the effect that making the drugs available might have on GP consultations. This could increase the costs and reduce the probability that the symptoms really were influenza. Again the numbers are lacking but the Committee considered that a rise of between 5% -15% was likely. This put the cost per QALY back up from \u00a38k to\u00a0 \u00a327k in NICE\u2019s 2003 appraisal<\/a>.<\/p>\n

In its 2009 appraisal<\/a> the Committee went one ingenious\u00a0 step further – it changed the Quality of Life loss due to influenza symptoms from 0.5 to 0.22 on the basis that the reduction in days with symptoms was likely to\u00a0 be at the end of the episode when symptoms were likely to be less severe.\u00a0 When hospitalisations and\u00a0 mortality benefits were excluded this resulted in a cost per QALY\u00a0 from \u00a340k to \u00a366k. On this basis it concluded that oseltamivir and zanamivir for the treatment of influenza in otherwise healthy adults would not be a cost effective use of NHS resources.<\/p>\n

Several points strike me as interesting:<\/p>\n