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LETTERS: Marc Brisson, W John Edmunds, Nigel J Gay, Elizabeth Miller, J Claire Bramley, Ruby Devi, David Muir, Philip Rice, A H Mohsen, M W McKendrick, Neil Roberts, Giles J Peek, Nikki Jones, Richard K Firmin, and Diana Elbourne Deaths from chickenpox BMJ 2002; 324: 609a [Full text]

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Deaths from chickenpox in adults

Norman Noah, WCIE 7HT   (17 April 2002)

Deaths from chickenpox in adults 17 April 2002
Norman Noah, Professor of Public Health LSHTM., WCIE 7HT Send response to journal: Re: Deaths from chickenpox in adults	EDITOR-It was good to hear[1] that the trend of an increasing number of deaths from chickenpox has reversed in the three years since we completed our survey[2]. However, Brisson et al [1] disagree with us for claiming that 'deaths in adults are rising' and furthermore, state that this 'is misleading'. Our conclusion that adult deaths had risen was based on statistics covering a period of 31 years, from 1967 to 1997. Of certified deaths from chickenpox, adults accounted for 48% in 1967-1977 [88 deaths 11years], 64% in 1978-1985 [120 deaths in 8 years] [3], and 81% in 1986-1997 [269 deaths in 12 years]. The contention that our data are misleading on the basis of three further years of data compared with our span of 31 years is less than impressive, and clearly needs to be placed in context. Moreover there is a precedent for periods of lower mortality, as discussed below for the period 1989-1991.The main body of our paper stated that deaths from chickenpox in adults have increased in number and proportion. We inadvertently used the present tense in the abstract and cannot claim to see into the future. We looked at ONS deaths for the 13-year period 1985-1997(table). This table which was not published in our paper for reasons of space shows that with the exception of two years the annual number of deaths was fairly consistent. The exceptions were 1989 and 1996 when the case fatality rates based on consultation rates to the RCGP were also exceptionally different. We have no explanation for this. However the total number of deaths in three year periods 1986-88. 1989-91, 1992-4, 1995-7 were 26, 22, 27, and 27 respectively. This does not show that, as Brisson et al [1] state, 'The number of deaths from chickenpox and case fatality rates were significantly higher in 1995-7 [the period of our study] than at any other period'. The overall case fatality rates in the table do not show this either. The main messages of our paper are that: mortality from chickenpox is not negligible; adults account for a high proportion of deaths; the number and proportion of adult deaths increased substantially between 1967 and 1997. Norman Noah Professor of Public Health 1. Brisson M, Edmunds WJ, Gay NJ, Miller E. Deaths from chickenpox in adults are decreasing. BMJ 2002; 324: 609. [9 March] 2. Rawson H, Crampin A, Noah N. Deaths from chickenpox in England and Wales 1995-7: analysis of routine mortality data. BMJ 2001; 323: 1091- 1093[10 November.] 3. Joseph CA, Noah N. Epidemiology of chickenpox in England and Wales, 1967-85. BMJ 1988; 296: 673-676 Table . Chickenpox certified deaths and estimated case-fatality rates (1985-1997) Year RCGP Rate per 100 000 No. of Cases in Population* ONS Certified Deaths Case Fatality Rate per 100 000 1985 544 271891 25 9.19 1986 556 278890 25 8.96 1987 514 258748 24 9.28 1988 621 313729 30 9.56 1989 699 354393 19 5.36 1990 552 280858 24 8.55 1991 554 283089 24 8.48 1992 653 334839 27 8.06 1993 643 330753 30 9.07 1994 623 321593 23 7.15 1995 484 250809 22 8.77 1996 597 310500 39 12.56 1997 486 253746 20 7.88 Average 579 276295 26 9.22 *Estimated number of cases of chickenpox in England and Wales based on RCGP consultation rates.