Tonsillectomy and acute throat infections in children

199 Pages·2015·19.11 MB·English

Tonsillectomy and acute throat infections
in children
Submitted for the Degree of Doctor of Philosophy
Dr Elizabeth Koshy
Department of Primary Care and Public Health
Imperial College London

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Abstract
Background: Tonsillectomy is among the most common operations performed on children in the UK. Yet little was
known about the socio-demographic profile of children who undergo the operation and how the recent decline in
tonsillectomy rates has influenced the rates of severe acute throat infections (ATI). Many children with mild ATI
disease also undergo tonsillectomy despite a lack of evidence of its benefit in this group, particularly in the
longer-term. The aims of this thesis were to characterise the socio-demographic profile of children who undergo
tonsillectomy and investigate the clinical impact of the operation on ATI in primary and secondary care settings.

Methods: The clinical spectrum of ATI in relation to tonsillectomy was investigated using a combination of
retrospective time-trend analyses and a retrospective cohort study. I analysed routine data from the Hospital
Episodes Statistics and Clinical Practice Research Datalink databases to investigate secondary care and primary
care settings, respectively.

Results: There was a 76% increase in ATI hospital admission rates among children between 1999/2000 and
2009/10 from 107.3 to 188.4 admissions per 100,000 children, respectively. However, the majority of these
children did not stay overnight and admission rates for peritonsillar abscess (PTA) remained stable. By contrast,
tonsillectomy rates fluctuated over the first three years of the study period, but declined overall from 367 to 294
per 100,000 children during the same study years. In general practice, tonsillectomy only modestly reduced the
frequency of subsequent ATI consultations among children with low baseline ATI consultation rates.

Conclusions: There does not appear to be a relationship between trends in tonsillectomy operations and
admissions for ATI or PTA at a population level, which suggests that clinicians should continue to restrict the
operation to children who are more severely affected by ATI disease. Additionally, tonsillectomy does not appear
to have a clinically significant benefit in reducing ATI consultations among children with mild ATI disease in the
longer-term, which further supports reserving the operation for children with severe ATI disease.

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Statement of contributions
I declare that the work presented in this thesis is my own. Where information has been derived from
other sources, this has been indicated and appropriately referenced.
Dr. Joanna Murray extracted the Hospital Episodes Statistics data and Dr. Vasa Curcin extracted the
Clinical Practice Research Datalink data for me to analyse.

Copyright declaration
The copyright of this thesis rests with the author and is made available under a Creative Commons
Attribution Non-Commercial No Derivatives licence. Researchers are free to copy, distribute or transmit
the thesis on the condition that they attribute it, that they do not use it for commercial purposes and
that they do not alter, transform or build upon it. For any reuse or redistribution, researchers must
make clear to others the licence terms of this work

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Acknowledgements
I am incredibly grateful to my supervisors, Dr. Sonia Saxena and Dr. Alex Bottle for their invaluable time,
providing extremely incisive comments and reading my thesis so carefully and meticulously.
Professor Azeem Majeed has supported and encouraged me prior to and during my PhD and I am very
much indebted to him.
Professor Mike Sharland’s clinical knowledge and wisdom were of tremendous help during my PhD.
I am very grateful to my colleagues and friends during the last few years and especially to Dr. Jo Murray
and Farzan Ramzan who have been wonderful colleagues and friends to me during this entire PhD.
I would not have been able to undertake this PhD if it was not for the support and encouragement of my
family. In particular, my loving and sacrificing parents, my wonderful husband and my inspirational
daughter. We have all shared the journey of highs and lows and all that accompanied it, including
outside life events during this time. Beyond learning about research, this PhD journey has served as a
valuable lesson about people and life!
Funding
I am eternally grateful to the National Institute for Health Research (NIHR) for funding my Doctoral
Research Fellowship. This PhD represents independent research and the views expressed are those of
the author(s) and not necessarily those of the NHS, NIHR or Department of Health
Ethical approval
My Clinical Practice Research Datalink research protocol was approved by the Independent Scientific
Advisory Committee (ISAC) and I obtained the data free of charge under the MRC licence scheme.
The Dr Foster Unit at Imperial College London has permission from the NIGB under Section 251 of the
NHS Act 2006 (formerly Section 60 approval from the Patient Information Advisory Group) to hold
confidential data. There is ethical approval to use the data for research purposes from the South East
Ethics Research Committee.
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Research outputs from this PhD
Original peer-reviewed publications directly relating to this work
1) Koshy E, Watt H, Curcin V, Bottle A, Sharland M, Saxena S. Tonsillectomy among children with
low baseline acute throat infection consultation rates in UK general practices: a cohort study.
BMJ Open 2015 Feb 3;5(2).

2) Koshy E, Bottle A, Murray J, Sharland M, Saxena S. Changing indications and socio-demographic
determinants of (adeno)tonsillectomy among children in England-are they linked? A
retrospective analysis of hospital data. PLoS One 2014 Aug 11;9(8).

3) Koshy E, Curcin V, Bottle A, Sharland M, Saxena S. Sore throat consultations in general practice
prior to tonsillectomy among eight hundred and sixty-three children in England: is this in
accordance with the SIGN guidelines? Clinical Otolaryngology 2013 Jun; 38(3):266-70.

4) Koshy E, Murray J, Bottle A, Aylin P, Sharland M, Majeed A, Saxena S. Significantly increasing
hospital admissions for acute throat infections among children in England: is this related to
tonsillectomy rates? Archives of Disease in Childhood 2012 Dec; 97(12):1064-8.
Other outputs during this time
1) Annual Report of the Chief Medical Officer. Volume Two (2011). Infections and the rise of
antimicrobial resistance. Chapter 6, Life stage: Perinatal (Invited co-author contribution).
2) Koshy E, Murray J, Bottle A, Sharland M, Saxena S. Validity of using Hospital Episodes Statistics
data on monitoring disease trends. Response. Thorax 2010 Vol:66, ISSN:0040-6376, Pages:827-
828.
3) Koshy E, Murray J, Bottle A, Sharland M, Saxena S. Impact of the seven-valent pneumococcal
conjugate vaccination (PCV7) programme on childhood hospital admissions for bacterial
pneumonia and empyema in England: national time-trends study, 1997-2008. Thorax 2010
Sep;65(9):770-4.

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Research conference presentations
 Poster presentation at the European Society of Paediatric Otolaryngologists (ESPO) in Dublin,
2014.
 Poster presentation at the World Organization of National Colleges, Academies and Academic
Associations of General Practitioners/Family Physicians (WONCA) GP conference in Prague, 2013.
 Oral presentation at the World Organization of National Colleges, Academies and Academic
Associations of General Practitioners/Family Physicians (WONCA) GP conference in Prague, 2013.
 Oral presentation at the Royal College of Paediatrics and Child Health (RCPCH) national annual
conference in Glasgow, 2012.
Invited oral presentations
 Invited oral presentation at the British Thoracic Society (BTS) national annual conference in
London, 2011.
 Invited oral presentation in the ‘Cutting Edge Research Session’ at the Royal College of General
Practitioners’ (RCGP) national annual conference in Harrogate, 2011.
Prizes and recognition during PhD
 Poster prize at Imperial College School of Public Health PhD Symposium, 2013.
 Royal College of General Practitioners’ (RCGP) Research paper of the year: Medicines for children
category, 2012.
 BBC Health News report: ‘Rise in child throat infections treated in hospital, study finds…’
(20th October 2012) http://www.bbc.co.uk/news/health-20002115
 Prize plenary at the Society for Academic Primary Care (SAPC) at the University of East Anglia,
Norwich, 2010.
 Early career award at the regional Society for Academic Primary Care (SAPC) in Cambridge, 2010.
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Table of Contents
Chapter 1 Introduction ......................................................................................................................... 13
1.1 Historical trends in tonsillectomy operations ............................................................................. 13
1.2 Childhood respiratory illness ....................................................................................................... 15
1.3 Acute throat infection presentations .......................................................................................... 15
1.4 Recurrent and chronic throat infections - criteria for referral for tonsillectomy ....................... 25
1.5 Indications for tonsillectomy ....................................................................................................... 27
1.6 Variation in tonsillectomy rates .................................................................................................. 30
1.7 Previous studies on the impact of tonsillectomy ........................................................................ 33
1.8 ENTUK’s position paper on tonsillectomy ................................................................................... 39
1.9 Challenges of ATI and tonsillectomy for families and primary care clinicians ............................ 39
1.10 Key findings from the literature review and the justification of this research ........................... 41
1.11 Scope of this thesis ...................................................................................................................... 42
1.12 Chapter summary ........................................................................................................................ 42
Chapter 2 Overview and rationale for this thesis ................................................................................ 43
2.1 Rationale for studies within secondary care ............................................................................... 43
2.2 Rationale for studies within primary care ................................................................................... 43
2.3 Rationale for Study 1: Socio-demographic profile of children undergoing tonsillectomy ......... 44
2.4 Rationale for Study 2: Relationship between tonsillectomy and ATI admission trends ............. 46
2.5 Rationale for Study 3: ATI consultation patterns prior to tonsillectomy .................................... 46
2.6 Rationale for Study 4: Impact of tonsillectomy on ATI consultations ......................................... 47
2.7 Overarching hypothesis of thesis ................................................................................................ 48
2.8 Main research questions ............................................................................................................. 48
2.9 Aim of thesis ................................................................................................................................ 48
2.10 Objectives .................................................................................................................................... 48
Chapter 3 Use of routinely collected data for research in children ..................................................... 50
3.1 Conducting child health research ................................................................................................ 50
3.2 Electronic Health Records (EHR) ................................................................................................. 50
3.3 Routinely collected datasets ....................................................................................................... 51
3.4 Study designs for child health research ...................................................................................... 52
3.5 Summary of chapter .................................................................................................................... 54
Chapter 4 Methodology and research tools ........................................................................................ 56
4.1 Hospital Episodes Statistics (Studies 1 and 2) ............................................................................. 56
4.2 Clinical Practice Research Datalink (Studies 3 and 4) .................................................................. 60
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4.3 Carstairs index of deprivation and the Index of Multiple Deprivation ....................................... 64
4.4 Statistical concepts and considerations ...................................................................................... 64
4.5 Definitions used within this thesis .............................................................................................. 65
4.6 Study 1: Socio-demographic profile of children undergoing tonsillectomy ............................... 67
4.7 Study 2: Relationship between tonsillectomy and ATI admission trends ................................... 70
4.8 Study 3: ATI consultation patterns prior to tonsillectomy .......................................................... 73
4.9 Study 4: Impact of tonsillectomy on ATI consultations ............................................................... 78
4.10 Summary of Chapter.................................................................................................................... 81
Chapter 5 Results ................................................................................................................................. 82
5.1 Study 1: Socio-demographic profile of children undergoing tonsillectomy ............................... 82
5.2 Study 2: Relationship between tonsillectomy and ATI admission trends ................................... 89
5.3 Study 3: ATI consultation patterns prior to tonsillectomy ........................................................ 102
5.4 Study 4: Impact of tonsillectomy on ATI consultations ............................................................. 107
Chapter 6 Discussion .......................................................................................................................... 113
6.1 Main findings of my thesis ........................................................................................................ 113
6.2 Strengths and limitations of individual studies ......................................................................... 114
6.3 Methodological implications of using these datasets ............................................................... 117
6.4 Possible explanations of my findings and comparison with other studies ............................... 121
6.5 Implications for practice and policy .......................................................................................... 133
6.6 Future research areas ................................................................................................................ 138
6.7 Conclusions ................................................................................................................................ 140
Chapter 7 References ......................................................................................................................... 141
Chapter 8 Appendices ........................................................................................................................ 154
Appendix 1: Key studies evaluating the impact of tonsillectomy included in this thesis ............... 155
Appendix 2: Peer reviewed publications and copyright permissions ............................................. 162

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Table of Tables
Table 1: The SIGN criteria for tonsillectomy for recurrent throat infections: 1999 and 2010 ........... 27
Table 2: Strengths and weaknesses of the Hospital Episodes Statistics database ............................. 58
Table 3: Strengths and weaknesses of the Clinical Practice Research Datalink database ................. 62
Table 4: Children who underwent tonsillectomy by age group and sex, 2001/2 (N= 29,697) ........... 84
Table 5: Children who underwent tonsillectomy by age group and sex, 2011/12 (N=27,732) ......... 84
Table 6: Tonsillectomy rates by age group, 2001/2 and 2011/12 ...................................................... 85
Table 7: Distribution of deprivation level among children who underwent tonsillectomy,
2001/2 (N=29,653)* .............................................................................................................. 85
Table 8: Distribution of deprivation level among children who underwent
tonsillectomy,2011/12 (N=27,610)* ..................................................................................... 86
Table 9: Sleep-disordered breathing and deprivation level among children who underwent
tonsillectomy (aged <4 years) ............................................................................................... 86
Table 10: Sleep-disordered breathing and deprivation level among children who underwent
tonsillectomy (aged 12-15 years) .......................................................................................... 87
Table 11: Annual age-standardised admission rates for acute throat infection, peritonsillar
abscess and tonsillectomy operations .................................................................................. 90
Table 12: Annual admission rates for boys and girls by age group for acute throat infection ............ 92
Table 13: Annual admission rates for boys and girls by age group for peritonsillar abscess .............. 94
Table 14: Annual admission rates for boys and girls by age group for tonsillectomy,
1999/2000 to 2009/10 .......................................................................................................... 96
Table 15: Annual admission rates for viral upper respiratory tract infections and all-cause
emergencies ........................................................................................................................ 100
Table 16: Documented consultation patterns for throat infections among children during 1
year prior to tonsillectomy .................................................................................................. 104
Table 17: Percentage of children who fulfilled the SIGN 1999 criteria for documented throat
infection consultations prior to tonsillectomy .................................................................... 105
Table 18: Characteristics of study population at baseline (1998-2001) in tonsillectomy and
comparison groups .............................................................................................................. 109
Table 19: Mean differences in acute throat infection consultations per child prior to and
subsequent to the index date in 2001 ................................................................................ 110
Table 20: Effect of tonsillectomy on the outcome of ≥3 and <3 acute throat infection
consultations at 1-3 years and 4-6 years follow-up ............................................................ 111
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Table of Figures
Figure 1: The clinical spectrum of illness for throat infections in children .......................................... 20
Figure 2: Overview of the individual studies within this thesis ........................................................... 49
Figure 3: Definitions used for acute throat infection documentation prior to tonsillectomy............. 76
Figure 4: Cohort study design showing time-frames studied .............................................................. 78
Figure 5: Flow diagram of cohort construction .................................................................................... 81
Figure 6: Annual tonsillectomy rates by age group (<4 years and 4-15 years), 2001/2 to
2011/12 ................................................................................................................................. 83
Figure 7: Annual age-standardised admission rates for acute throat infection and
tonsillectomy operations, 1999/2000 to 2009/10 ................................................................ 91
Figure 8: Emergency admission rates for acute throat infection for boys and girls by age
group, 1999/2000 to 2009/10 ............................................................................................... 91
Figure 9: Annual tonsillectomy rates for boys and girls by age group, 1999/2000 to 2009/10 .......... 95
Figure 10: Annual admission rates for acute throat infection with short and long hospital
stays, 1999/2000 to 2009/10 ................................................................................................ 97
Figure 11: Age group-specific tonsillectomy (1-4 years) and acute throat infection admission
(5-9 years) rates by year ........................................................................................................ 98
Figure 12: Age group-specific tonsillectomy (5-9 years) and acute throat infection admission
(10-14 years) rates by year.................................................................................................... 99

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