Hernia DOI 10.1007/s10029-014-1314-9
ORIGINAL ARTICLE
Trends in operation rates for inguinal hernia over five decades in England: database study J. J. Maisonneuve • D. Yeates • M. J. Goldacre
Received: 21 November 2013 / Accepted: 22 October 2014 Ó Springer-Verlag France 2014
Abstract Purpose We aimed to study trends over time in operation rates for inguinal hernia with and without obstruction over five decades. Methods Routine hospital statistics were used to analyse trends in National Health Service hospitals in England (1968–2011). Results All-England admission rates for elective repair of unobstructed inguinal hernia in males were 240.8 episodes per 100,000 population [95 % confidence interval (CI) 234.5–247.2] in 1968 and were relatively stable until 2003 after which they declined to 217.1 (215.4–218.8) by 2011. However, the stability of the all ages rates masked a large decline in admission rates in the young (e.g. 425 per 100,000 in 1968–1970 in males under 1 year of age, down to 155 per 100,000 in 2007–2011) and a large increase in the elderly (e.g. 247 in 1968–1970 per 100,000 males aged 75–84, up to 799 per 100,000 in 2007–2011). All-England admission rates for obstructed inguinal hernia in males almost halved, from 19.3 episodes (17.4–21.2) in 1968 to 10.7 episodes (10.3–11.0) per 100,000 population in 2011.
Electronic supplementary material The online version of this article (doi:10.1007/s10029-014-1314-9) contains supplementary material, which is available to authorized users. J. J. Maisonneuve D. Yeates M. J. Goldacre (&) Unit of Health–Care Epidemiology, Nuffield Department of Population Health, Oxford University, Old Road Campus, Headington, Oxford OX3 7LF, UK e-mail: [email protected] J. J. Maisonneuve e-mail: [email protected] D. Yeates e-mail: [email protected]
Admission rates for females gradually declined over time for both unobstructed and obstructed inguinal hernia. Conclusion Hospital admission rates for elective operation on inguinal hernia without obstruction, for all ages combined, have been relatively stable over five decades, but this masked big differences between age groups. Rates of obstructed hernia have declined over time, particularly in the early years covered by the study, and have not shown an increase associated with the recent fall in elective surgery for hernia repair. Keywords England
Inguinal hernia Hospital admission
Introduction Inguinal hernia repair is among the most common surgical procedures [1–3]. It is performed to relieve discomfort and to avoid subsequent strangulation. In the past, it has been thought that some cases of inguinal hernia are precipitated by exertion and high intra-abdominal pressure but this is uncertain and controversial [4]. Some inguinal hernias are congenital, apparent at birth, and are more common in infants with low birth weight [5]. In the past, operations were delayed until the infant was at least 6 months old [6], but now repair in infants commonly occurs shortly after diagnosis to avoid subsequent incarceration [7]. A consensus as to the optimal timing of repair has not been reached [7]. For adults, changes to European guidelines and National Health Service (NHS) policy in England in recent years have meant that decisions to operate on inguinal hernia in men who are minimally symptomatic may now take a lower priority than in the past [8, 9].
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Hernia
Methods
350
Per 100,000 populaon
Our aim was to document trends over time in operation rates for inguinal hernia with and without obstruction, in men and women, in England. We also analysed trends in inguinal hernia repair for individual age groups. As well as a general interest in the trends, we wanted to know if any decline in elective surgery in recent years has been accompanied by any increase in rate of obstruction.
300 250 200 150 100 50
123
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2011
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1999
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1990
1993
1984
1987
1981
1975
1978
1969
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1966
1963
0
Information on hospital admissions in the National Health Service (NHS) in England is collected routinely. We analysed national hospital admission rates using hospital statistics for all England available between 1968 and 2011. The all-England data from 1968 to 1985 were collected on a national sample of one in ten admissions to hospital, excluding day cases (the term in England for same day admission and discharge), for the whole of England in a system called the Hospital Inpatient Enquiry (HIPE). We scaled up these by multiplying the numbers by ten. National data were not collected between 1986 and 1989. From 1990, English data covered all NHS hospital admissions (not just a sample), including day cases, as the Hospital Episode Statistics (HES) system. HES data were provided to us by the NHS Health and Social Care Information System (which was unable to provide data for 2012 or 2013). We also analysed the dataset of the Oxford Record Linkage Study (ORLS) which covers part of southern England. We did so because it has a longer time span of hospital statistics than the all-England datasets, beginning in 1963; there were no breaks in data collection, unlike the all-England dataset; no sampling was used—it was based on 100 % of patients; day cases were included throughout (unlike national HIPE); and the data were linked (see below) throughout the span of ORLS. Furthermore, as the pre-1986 ORLS data and HIPE were independent of each other, the findings in these datasets can be used to corroborate each other for the early years of the study. The ORLS includes hospital admissions in the former Oxford NHS Region Health Authority area. The boundaries of data coverage increased over time: from 1963, it included just part of Oxfordshire; from 1966, it included Oxfordshire and West Berkshire (850,000 people) and by 1991, the whole region (2.5 million people) was covered. Episode-based admission rates refer to each hospital admission, and a person will have multiple episodes counted if they are admitted more than once or transferred between hospitals. Person-based admission rates refer to individual people in receipt of care where multiple admissions for an individual are linked and counted as one
Year of Admission Male naonal episodes
Male ORLS people
Female ORLS people
Female naonal episodes
Fig. 1 Hospital admission rates for inguinal hernia without obstruction, in males and females, 1963–2011, England and the Oxford region, per 100,000 population
person. Record linkage of national data, to count people, is available between 1999 and 2011; record linkage of the ORLS dataset spans its whole length, 1963–2011. Admission rates were standardised for age, in five-year age groups, using the direct method and the European standard population. 95 % confidence intervals (CI) of the admission rate were calculated. To identify all cases of inguinal hernia from 1963 to 2011, the International Classification of Disease (ICD) codes from the 7th, 8th, 9th, and 10th revisions were used. The ICD codes used for inguinal hernia with obstruction were: ICD 7 561, ICD 8 552, ICD 9 550.0-550.1, and ICD 10 K40.0, 1, 3, and 4. The ICD codes for inguinal hernia without obstruction were ICD 7 560, ICD 8 550 and 544, ICD 9 550.9, ICD 10 K40.9 and K40.2, in combination with operation codes for elective inguinal hernia repair identified as Office of Population Censuses and Surveys (OPCS) code 402 (OPCS version (v) 1), OPCS 411 and 415 (v2), 411 and 415 (v3), and T20 and T21 (v4).
Results Inguinal hernia without obstruction There were 1,598,002 hospital episodes in England for inguinal hernia without obstruction between 1968 and 2011, with 898,437 episodes for 889,931 people admitted between 1999 and 2011. In the Oxford region, there were 122,992 episodes for 121,624 people between 1963 and 2011. Males comprised 92.5 % of unobstructed admissions nationally and 91.8 % of admissions in the Oxford region.
Hernia
Per 100,000 populaon
30 25 20 15 10 5
1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011
0
Year of admission Male naonal episodes
Male ORLS people
Female ORLS people
Female naonal episodes
Fig. 2 Hospital admission rates for inguinal hernia with obstruction, in males and females, 1963–2011, England and the Oxford region, per 100,000 population
Annual hospital admission rates, in England and the Oxford region, for inguinal hernia without obstruction are shown in Fig. 1. National admission rates for men were largely stable over time, but showed a gradual decline after 2003. In 1968, the national annual admission rate was 240.8 (95 % CI 234.5–247.2), 248.4 in 2003, and by 2011 it had fallen to 217.1 episodes (95 % CI 215.4–218.8) per male 100,000 population. The dip in operation rates in 1975 was associated with widespread labour strikes in the NHS which reduced elective admissions to hospitals. In 1963, admission rates for men in the Oxford region were 243.6 people (95 % CI 219.2–267.9) and fluctuated within the range of 215.9–293.3 people until 2003 when they sharply declined. By 2011, the rate had fallen to 170.4 people (95 % CI 163.9–176.8) per 100,000 male population (Fig. 1). Admission rates for women have gradually declined over time. Nationally, in 1968, there were 21.9 episodes (95 % CI 20.1–23.8) and in 2011, there were 15.3 episodes (95 % CI 14.9–15.8) per 100,000 female population. In Oxford admission rates declined from 32.1 (95 % CI 23.2–40.9) in 1963, to 9.4 women (95 % CI 7.9–10.9) in 2011, per 100,000 female population. Inguinal hernia with obstruction For inguinal hernia with obstruction in the all-England dataset, there were 84,902 episodes nationally between 1968 and 2011, with 46,301 episodes for 44,186 people between 1999 and 2011. In the Oxford region, there were 6,025 episodes for 5,825 people admitted from 1963 to 2011. Males comprised 87.4 % of admissions for
obstructed inguinal hernia both nationally and in the Oxford region. Figure 2 shows the hospital admission rates for inguinal hernia with obstruction in England and the Oxford region. English national data showed a decline in admission rates for males from 19.3 episodes (95 % CI 17.4–21.2) in 1968 to 10.7 episodes (95 % CI 10.3–11.0) per male 100,000 population in 2011 (Fig. 2). Admission rates for men in the Oxford region were 24.0 people per 100,000 male population (95 % CI 19.1–30.1) in 1968 and they had fallen to 10.8 by 1974. In 2011, the admission rate in the Oxford region was 9.0 people per male 100,000 population (95 % CI 7.6–10.5). The rate of hospital admission for women has gradually declined over time both nationally and in the Oxford region. In 2011, there were 1.34 episodes nationally (95 % CI 1.2–1.5), and 0.74 people (95 % CI 0.3–1.1) in the Oxford region, per female 100,000 population.
National trends over time by age groups We report on trends by age group for national all-England hospital admissions (Table 1; results for the Oxford region were similar and are available online as Supplementary Material). Inguinal hernia without obstruction The trajectory of admission rates over time differed by age group in males (Table 1). Rates for male infants aged under 1 year and male children between 1 and 14 years showed a big decline. Rates for people aged 15–64 slightly declined. Men aged over 65 showed a substantial increase over time. For females under 1 year, numbers were small and rates fluctuated. Rates fell for females in age groups 1–14, 15–44 and 45–64 years. There was an increase in admission rates for inguinal hernia without obstruction over time for females over 65. Inguinal hernia with obstruction Table 2 shows a large fall in admission rates for hernia with obstruction in male infants and in male children aged 1–14. There was no convincing evidence of consistent declines in females in these age groups. The trend was rather inconsistent in males aged 15–44; but there were clear declines in males in the older age groups (Table 2). For females, there were falls in the age groups 45–64, 65–74 and 75–84, particularly in the early years (Table 2). In the younger and oldest age groups, declines were not so evident.
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Hernia Table 1 National age- and sexspecific rates of hospital admission episodes for inguinal hernia without obstruction per 100,000 population in each age– sex group, with percentage change comparing the last period with the first
95 % CI \1
1–14
15–44
45–64
65–74
75–84
85?
All
Lower
Upper
1968–1970
425.1
151.1
144.9
442.8
421.9
247.1
231.1
248.4
244.7
252.1
1971–1975
602.7
148.1
130.0
416.7
429.7
318.2
260.9
240.9
238.1
243.7
1976–1980
738.1
137.6
111.3
446.9
530.8
436.1
320.7
251.8
248.9
254.7
1981–1985
743.9
136.6
95.1
424.8
635.6
660.8
478.1
255.0
252.1
258.0
1990–1996
227.9
44.7
114.5
415.4
756.1
859.6
599.2
249.4
248.6
250.2
1997–2001
109.8
20.3
131.8
404.5
723.3
818.3
597.0
243.5
242.4
244.6
2002–2006
100.6
16.7
132.3
398.3
723.2
828.3
589.5
241.5
240.7
242.4
2007–2011
154.9
17.1
125.6
369.5
688.5
798.8
546.9
228.7
227.9
229.5
36.4
11.3
86.7
83.4
163.2
323.2
236.6
1968–1970
29.6
22.2
15.3
30.8
32.8
27.3
23.3
22.5
21.4
23.6
1971–1975
47.7
26.0
11.8
25.1
29.1
28.2
16.9
20.4
19.6
21.2
1976–1980
95.0
28.4
10.1
23.1
30.8
35.5
25.5
20.8
20.0
21.6
1981–1985
123.9
28.4
10.7
23.4
37.9
48.3
38.2
22.6
21.7
23.4
1990–1996
25.1
10.8
8.9
23.0
38.9
56.8
45.6
17.0
16.8
17.2
1997–2001
23.9
5.8
9.2
22.7
41.9
57.8
48.1
16.2
16.0
16.5
2002–2006 2007–2011
18.4 29.1
5.2 6.3
9.4 9.0
21.2 19.9
44.1 44.7
64.7 67.5
49.5 49.4
16.1 16.2
15.9 15.9
16.3 16.4
98.3
28.4
58.7
64.4
136.4
247.3
212.4
Male
Rate in 2007–2011 as a percentage of rate in 1968–1970 Female
Rate in 2007–2011 as a percentage of rate in 1968–1970
Discussion
recent years was associated with an increase in obstructed inguinal hernia.
Main findings Interpretation Hospital admission rates for elective repair of inguinal hernia without obstruction in men were reasonably stable, overall, until the mid 2000s when they declined. Overall, admission rates for women with inguinal hernia without obstruction have gradually declined over time. However, there were very substantial differences between the age groups in trends over time. These differences largely ‘cancelled each other out’ at the all ages level, giving the appearance of little change when, in fact, change in some individual age groups has been considerable. There was a decline in admission rates in male infants (though not in female infants). Children aged 1–14, both males and females, experienced a decline in admission rates over time, notably from the mid 1980s. For men with obstructed inguinal hernia, hospital admission rates dropped from the 1960s to the 1980s and then levelled off remaining relatively stable throughout the rest of the study period. There was no evidence that the decline in elective hernia repair in
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Admission rates for elective repair are a product of incidence and prevalence of inguinal hernia, referral to surgical care, and willingness to consider operation by both the patient and the surgeon. The decline in rates of elective repair in male children, and notably in those aged under 1 year, might reflect a decline in the birth prevalence of inguinal hernia. We encourage others, internationally, to study whether there has been a decline in admission rates for inguinal hernia in infants and children, and a decline in the birth prevalence of inguinal hernia, elsewhere. The rise in rates in the elderly may reflect both an increase in occurrence of hernia and increased availability and use (until the most recent years) of surgery for it. We give age-specific and age-standardised rates which take account of the ageing of the population. However, the fact that the population is ageing means that, overall, the
Hernia Table 2 National age- and sexspecific rates of hospital admission episodes for inguinal hernia with obstruction per 100,000 population in each age– sex group, with percentage change comparing the last period with the first
95 % CI \1
1–14
15–44
45–64
65–74
75–84
85?
All
Lower
Upper
1968–1970
171.3
12.7
3.9
14.8
41.6
108.8
227.9
19.1
18.0
20.2
1971–1975
142.5
6.9
2.8
12.9
42.6
99.3
186.1
15.9
15.2
16.7
1976–1980
136.6
5.9
2.5
10.4
37.9
109.2
240.6
15.4
14.6
16.2
1981–1985
137.9
5.6
1.9
11.3
36.0
97.5
216.2
14.6
13.9
15.3
1990–1996
114.7
4.6
2.6
9.6
30.3
78.9
174.0
12.5
12.3
12.6
1997–2001
85.2
3.5
3.0
9.5
31.2
72.3
154.9
11.6
11.4
11.8
2002–2006
68.8
2.6
3.4
9.4
29.8
69.7
141.1
11.0
10.8
11.1
2007–2011
69.9
2.4
3.1
9.6
28.4
66.3
132.3
10.6
10.4
10.8
40.8
18.4
80.6
64.5
68.2
60.9
58.0
1968–1970
3.3
0.3
0.4
2.4
5.4
10.3
17.5
1.8
1.5
2.0
1971–1975
9.3
0.3
0.3
1.7
4.4
13.0
18.0
1.6
1.4
1.9
1976–1980
12.1
0.3
0.2
1.2
3.7
10.0
18.7
1.4
1.2
1.6
1981–1985
14.5
0.4
0.2
1.1
4.3
10.4
16.5
1.5
1.3
1.7
1990–1996
10.5
0.3
0.2
1.0
2.7
7.8
16.9
1.1
1.1
1.2
1997–2001
11.2
0.3
0.2
1.0
2.9
7.5
14.6
1.1
1.1
1.2
2002–2006 2007–2011
8.9 9.9
0.4 0.3
0.2 0.2
0.9 1.0
2.9 3.6
8.5 9.2
16.5 18.6
1.1 1.3
1.1 1.2
1.2 1.3
299.7
100.0
51.2
42.6
67.3
88.7
106.3
With obstruction Male
Rate in 2007–2011 as a percentage of rate in 1968–1970 Female
Rate in 2007–2011 as a percentage of rate in 1968–1970
volume of care for hernia repair in the elderly has gone up more than the age-adjusted rates would indicate. A population-based record linkage study in Denmark, between 2006 and 2010, found that the prevalence of inguinal hernia was highest for those under 5 years old and those between 75 and 80 years old [10]. Previous record linkage studies examining emergent inguinal hernia repair in the Oxford region (1976–1986) and Minnesota (1989–2008) have found a declining trend in repair in males over time [3, 11]. The US research also found a gradual decline of emergent inguinal hernia repair among women [11]. The reason for the decline that we have observed in operation rates for obstructed hernia is unclear. However, a likely explanation is that an increase in the repair of unobstructed hernia in older men—the increase we have observed as a trend over time in operation rates on older men—has led to a reduced ‘prevalence pool’ of men with hernia at risk of obstruction. The decline in recent years in the rate of inguinal hernia without obstruction in males may be a result of a change in clinical guidelines following publication of new clinical evidence [9]. In 2006, a randomised control trial in the US provided evidence for observance, rather than surgical repair, of inguinal hernia
in men who are minimally symptomatic [12]. This evidence was incorporated into policy in England in 2006 [8].
Strengths and weaknesses We provide data on trends in inguinal hernia with and without obstruction over a five-decade period, using the longest runs of English statistics available. The study is reliant on the accuracy of clinical coding. Data on accuracy are not readily available; but the data collection systems for the ORLS and HIPE, covering the early decades of the study, were independent of each other; and the rates in each dataset are similar and they corroborate one another. Our results do not include inguinal hernia repair that was treated privately, and our study would have underestimated the true number of admissions. Data on the number of hernia operations undertaken in private non-NHS facilities in England are not available. Most non-NHS care will be used by people who are covered by private health insurance. The percentage of the UK population covered by private health insurance is small but rising: it was 3.2 % in 1968 and 10.6 % in 2006 (it peaked at 11.7 % in 2000). [3]
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It seems unlikely that this modest increase will have impacted much on the large changes seen in our data within individual age groups. Insofar as it may have contributed, its effect would be that the large increases in elective operation rates in the elderly would have been underestimated by our data. Private care, rather than NHS care, is uncommonly used for children or for emergency treatment. Day case care was not included in routine national statistics from 1968 to 1989, although it was included in the Oxford data from its inception and in national statistics from 1990 to 2011. The fact that there was no abrupt increase in the rates in England in 1990, when day cases began to be captured in English HES, suggests that moves from inpatient to day case care did not impact on the overall (day case plus inpatient) rates.
Conclusion Over the past five decades, operation rates for inguinal hernia without obstruction have been largely stable over time, but with big differences between age groups and between males and females. The rate of admission of children has declined substantially over time. The rate of admission for men over 65 has increased substantially over time. There was a large decline in admissions and operations for obstructed inguinal hernia in the 1960s and 1970s in adult males, with a further but smaller decline since then in men aged over 65. Admissions for obstructed hernia have not risen recently, following the recent decline in elective surgery, but this should be monitored in future. Acknowledgments The Unit of Health-Care Epidemiology was funded by the English National Institute for Health Research to build the datasets (grant number RNC/035/02). MJG is part-funded by Public Health England. The views expressed in this paper do not necessarily reflect those of the funding bodies. Conflict of interest The authors declare no conflicts of interest. This was an independent study; the funding source had no involvement in the study design, data collection, data analysis and interpretation, writing of the report, or the decision to submit the article for publication. The views expressed are not necessarily those of the funding body.
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Ethical Standards Ethical approval for a multi-purpose programme of work analyzing these anonymised datasets was obtained from the UK National Research Ethics Service (04/Q2006/176).
References 1. Kingsnorth A, LeBlanc K (2003) Hernias: inguinal and incisional. Lancet 362:1561–1571 2. National Institute of Clinical Excellence (NICE) (2004) Technology appraisal guidance 83: Laparoscopic surgery for inguinal hernia repair. NICE, London. http://www.nice.org.uk/nicemedia/ live/11542/32924/32924.pdf. Accessed 4 Oct 2013 3. Primatesta P, Goldacre MJ (1996) Inguinal hernia repair: incidence of elective and emergency surgery, readmission and mortality. Int J Epidemiol 25:835–894 4. O’Rourke MG, O’Rourke TR (2012) Inguinal hernia: aetiology, diagnosis, post-repair pain and compensation. ANZ J Surg 82(4):201–206. doi:10.1111/j.1445-2197.2011.05755.x (Epub 2011 Apr 25. Review. PMID:22510174) 5. Powell TG, Hallows JA, Cooke RWI, Pharoah POD (1986) Why do so many small infants develop an inguinal hernia? Arch Dis Child 61:991–995 6. Wilkinson AW, Arneil TA (1978) Surgical aspects of paediatrics. In: Forfar JO, Gavin AC (eds) Textbook of paediatrics, 2nd edn. Churchill Livingstone, New York, p 1588 7. Wang KS (2012) Committee on fetus and newborn and section on surgery. Assessment and management of inguinal hernia in infants. Pediatrics 130:768–773 8. Thames Valley Priorities Committees (Oxfordshire PCTs) (2006) Policy statement 68a: elective surgery for the treatment of inguinal hernia in adults, Ref TV51. http://www.oxfordshireccg. nhs.uk/wp-content/uploads/2013/03/PS68-Inguinal-hernia-sur gery.pdf. Accessed 9 Sept 2014 9. Simons MP, Aufenacker T, Bay-Nielsen M et al (2009) European Hernia Society guidelines on the treatment of inguinal hernia in adult patients. Hernia 4:343–403 10. Burcharth J, Pedersen M, Bisgaard T, Pedersen C, Rosenberg J (2013) Nationwide prevalence of groin hernia repair. PLoS One 8:1–6 11. Hernandez-Irizarry R, Zendejas B, Ramirez T et al (2012) Trends in emergent inguinal hernia surgery in Olmsted County, MN: a population-based study. Hernia 16:397–403 12. Fitzgibbons Rj G-HAGJO et al (2006) Watchful waiting vs repair of inguinal hernia in minimally symptomatic men: a randomized clinical trial. JAMA 295:285–292 13. Hawe K (2009) Private Health Care. In: Hawe E (ed) Office of Health Economics Compendium of Health Statistics. Radcliffe Publishing Ltd, Abingdon, pp 125–132
ORIGINAL ARTICLE
Trends in operation rates for inguinal hernia over five decades in England: database study J. J. Maisonneuve • D. Yeates • M. J. Goldacre
Received: 21 November 2013 / Accepted: 22 October 2014 Ó Springer-Verlag France 2014
Abstract Purpose We aimed to study trends over time in operation rates for inguinal hernia with and without obstruction over five decades. Methods Routine hospital statistics were used to analyse trends in National Health Service hospitals in England (1968–2011). Results All-England admission rates for elective repair of unobstructed inguinal hernia in males were 240.8 episodes per 100,000 population [95 % confidence interval (CI) 234.5–247.2] in 1968 and were relatively stable until 2003 after which they declined to 217.1 (215.4–218.8) by 2011. However, the stability of the all ages rates masked a large decline in admission rates in the young (e.g. 425 per 100,000 in 1968–1970 in males under 1 year of age, down to 155 per 100,000 in 2007–2011) and a large increase in the elderly (e.g. 247 in 1968–1970 per 100,000 males aged 75–84, up to 799 per 100,000 in 2007–2011). All-England admission rates for obstructed inguinal hernia in males almost halved, from 19.3 episodes (17.4–21.2) in 1968 to 10.7 episodes (10.3–11.0) per 100,000 population in 2011.
Electronic supplementary material The online version of this article (doi:10.1007/s10029-014-1314-9) contains supplementary material, which is available to authorized users. J. J. Maisonneuve D. Yeates M. J. Goldacre (&) Unit of Health–Care Epidemiology, Nuffield Department of Population Health, Oxford University, Old Road Campus, Headington, Oxford OX3 7LF, UK e-mail: [email protected] J. J. Maisonneuve e-mail: [email protected] D. Yeates e-mail: [email protected]
Admission rates for females gradually declined over time for both unobstructed and obstructed inguinal hernia. Conclusion Hospital admission rates for elective operation on inguinal hernia without obstruction, for all ages combined, have been relatively stable over five decades, but this masked big differences between age groups. Rates of obstructed hernia have declined over time, particularly in the early years covered by the study, and have not shown an increase associated with the recent fall in elective surgery for hernia repair. Keywords England
Inguinal hernia Hospital admission
Introduction Inguinal hernia repair is among the most common surgical procedures [1–3]. It is performed to relieve discomfort and to avoid subsequent strangulation. In the past, it has been thought that some cases of inguinal hernia are precipitated by exertion and high intra-abdominal pressure but this is uncertain and controversial [4]. Some inguinal hernias are congenital, apparent at birth, and are more common in infants with low birth weight [5]. In the past, operations were delayed until the infant was at least 6 months old [6], but now repair in infants commonly occurs shortly after diagnosis to avoid subsequent incarceration [7]. A consensus as to the optimal timing of repair has not been reached [7]. For adults, changes to European guidelines and National Health Service (NHS) policy in England in recent years have meant that decisions to operate on inguinal hernia in men who are minimally symptomatic may now take a lower priority than in the past [8, 9].
123
Hernia
Methods
350
Per 100,000 populaon
Our aim was to document trends over time in operation rates for inguinal hernia with and without obstruction, in men and women, in England. We also analysed trends in inguinal hernia repair for individual age groups. As well as a general interest in the trends, we wanted to know if any decline in elective surgery in recent years has been accompanied by any increase in rate of obstruction.
300 250 200 150 100 50
123
2008
2011
2005
1999
2002
1996
1990
1993
1984
1987
1981
1975
1978
1969
1972
1966
1963
0
Information on hospital admissions in the National Health Service (NHS) in England is collected routinely. We analysed national hospital admission rates using hospital statistics for all England available between 1968 and 2011. The all-England data from 1968 to 1985 were collected on a national sample of one in ten admissions to hospital, excluding day cases (the term in England for same day admission and discharge), for the whole of England in a system called the Hospital Inpatient Enquiry (HIPE). We scaled up these by multiplying the numbers by ten. National data were not collected between 1986 and 1989. From 1990, English data covered all NHS hospital admissions (not just a sample), including day cases, as the Hospital Episode Statistics (HES) system. HES data were provided to us by the NHS Health and Social Care Information System (which was unable to provide data for 2012 or 2013). We also analysed the dataset of the Oxford Record Linkage Study (ORLS) which covers part of southern England. We did so because it has a longer time span of hospital statistics than the all-England datasets, beginning in 1963; there were no breaks in data collection, unlike the all-England dataset; no sampling was used—it was based on 100 % of patients; day cases were included throughout (unlike national HIPE); and the data were linked (see below) throughout the span of ORLS. Furthermore, as the pre-1986 ORLS data and HIPE were independent of each other, the findings in these datasets can be used to corroborate each other for the early years of the study. The ORLS includes hospital admissions in the former Oxford NHS Region Health Authority area. The boundaries of data coverage increased over time: from 1963, it included just part of Oxfordshire; from 1966, it included Oxfordshire and West Berkshire (850,000 people) and by 1991, the whole region (2.5 million people) was covered. Episode-based admission rates refer to each hospital admission, and a person will have multiple episodes counted if they are admitted more than once or transferred between hospitals. Person-based admission rates refer to individual people in receipt of care where multiple admissions for an individual are linked and counted as one
Year of Admission Male naonal episodes
Male ORLS people
Female ORLS people
Female naonal episodes
Fig. 1 Hospital admission rates for inguinal hernia without obstruction, in males and females, 1963–2011, England and the Oxford region, per 100,000 population
person. Record linkage of national data, to count people, is available between 1999 and 2011; record linkage of the ORLS dataset spans its whole length, 1963–2011. Admission rates were standardised for age, in five-year age groups, using the direct method and the European standard population. 95 % confidence intervals (CI) of the admission rate were calculated. To identify all cases of inguinal hernia from 1963 to 2011, the International Classification of Disease (ICD) codes from the 7th, 8th, 9th, and 10th revisions were used. The ICD codes used for inguinal hernia with obstruction were: ICD 7 561, ICD 8 552, ICD 9 550.0-550.1, and ICD 10 K40.0, 1, 3, and 4. The ICD codes for inguinal hernia without obstruction were ICD 7 560, ICD 8 550 and 544, ICD 9 550.9, ICD 10 K40.9 and K40.2, in combination with operation codes for elective inguinal hernia repair identified as Office of Population Censuses and Surveys (OPCS) code 402 (OPCS version (v) 1), OPCS 411 and 415 (v2), 411 and 415 (v3), and T20 and T21 (v4).
Results Inguinal hernia without obstruction There were 1,598,002 hospital episodes in England for inguinal hernia without obstruction between 1968 and 2011, with 898,437 episodes for 889,931 people admitted between 1999 and 2011. In the Oxford region, there were 122,992 episodes for 121,624 people between 1963 and 2011. Males comprised 92.5 % of unobstructed admissions nationally and 91.8 % of admissions in the Oxford region.
Hernia
Per 100,000 populaon
30 25 20 15 10 5
1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011
0
Year of admission Male naonal episodes
Male ORLS people
Female ORLS people
Female naonal episodes
Fig. 2 Hospital admission rates for inguinal hernia with obstruction, in males and females, 1963–2011, England and the Oxford region, per 100,000 population
Annual hospital admission rates, in England and the Oxford region, for inguinal hernia without obstruction are shown in Fig. 1. National admission rates for men were largely stable over time, but showed a gradual decline after 2003. In 1968, the national annual admission rate was 240.8 (95 % CI 234.5–247.2), 248.4 in 2003, and by 2011 it had fallen to 217.1 episodes (95 % CI 215.4–218.8) per male 100,000 population. The dip in operation rates in 1975 was associated with widespread labour strikes in the NHS which reduced elective admissions to hospitals. In 1963, admission rates for men in the Oxford region were 243.6 people (95 % CI 219.2–267.9) and fluctuated within the range of 215.9–293.3 people until 2003 when they sharply declined. By 2011, the rate had fallen to 170.4 people (95 % CI 163.9–176.8) per 100,000 male population (Fig. 1). Admission rates for women have gradually declined over time. Nationally, in 1968, there were 21.9 episodes (95 % CI 20.1–23.8) and in 2011, there were 15.3 episodes (95 % CI 14.9–15.8) per 100,000 female population. In Oxford admission rates declined from 32.1 (95 % CI 23.2–40.9) in 1963, to 9.4 women (95 % CI 7.9–10.9) in 2011, per 100,000 female population. Inguinal hernia with obstruction For inguinal hernia with obstruction in the all-England dataset, there were 84,902 episodes nationally between 1968 and 2011, with 46,301 episodes for 44,186 people between 1999 and 2011. In the Oxford region, there were 6,025 episodes for 5,825 people admitted from 1963 to 2011. Males comprised 87.4 % of admissions for
obstructed inguinal hernia both nationally and in the Oxford region. Figure 2 shows the hospital admission rates for inguinal hernia with obstruction in England and the Oxford region. English national data showed a decline in admission rates for males from 19.3 episodes (95 % CI 17.4–21.2) in 1968 to 10.7 episodes (95 % CI 10.3–11.0) per male 100,000 population in 2011 (Fig. 2). Admission rates for men in the Oxford region were 24.0 people per 100,000 male population (95 % CI 19.1–30.1) in 1968 and they had fallen to 10.8 by 1974. In 2011, the admission rate in the Oxford region was 9.0 people per male 100,000 population (95 % CI 7.6–10.5). The rate of hospital admission for women has gradually declined over time both nationally and in the Oxford region. In 2011, there were 1.34 episodes nationally (95 % CI 1.2–1.5), and 0.74 people (95 % CI 0.3–1.1) in the Oxford region, per female 100,000 population.
National trends over time by age groups We report on trends by age group for national all-England hospital admissions (Table 1; results for the Oxford region were similar and are available online as Supplementary Material). Inguinal hernia without obstruction The trajectory of admission rates over time differed by age group in males (Table 1). Rates for male infants aged under 1 year and male children between 1 and 14 years showed a big decline. Rates for people aged 15–64 slightly declined. Men aged over 65 showed a substantial increase over time. For females under 1 year, numbers were small and rates fluctuated. Rates fell for females in age groups 1–14, 15–44 and 45–64 years. There was an increase in admission rates for inguinal hernia without obstruction over time for females over 65. Inguinal hernia with obstruction Table 2 shows a large fall in admission rates for hernia with obstruction in male infants and in male children aged 1–14. There was no convincing evidence of consistent declines in females in these age groups. The trend was rather inconsistent in males aged 15–44; but there were clear declines in males in the older age groups (Table 2). For females, there were falls in the age groups 45–64, 65–74 and 75–84, particularly in the early years (Table 2). In the younger and oldest age groups, declines were not so evident.
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Hernia Table 1 National age- and sexspecific rates of hospital admission episodes for inguinal hernia without obstruction per 100,000 population in each age– sex group, with percentage change comparing the last period with the first
95 % CI \1
1–14
15–44
45–64
65–74
75–84
85?
All
Lower
Upper
1968–1970
425.1
151.1
144.9
442.8
421.9
247.1
231.1
248.4
244.7
252.1
1971–1975
602.7
148.1
130.0
416.7
429.7
318.2
260.9
240.9
238.1
243.7
1976–1980
738.1
137.6
111.3
446.9
530.8
436.1
320.7
251.8
248.9
254.7
1981–1985
743.9
136.6
95.1
424.8
635.6
660.8
478.1
255.0
252.1
258.0
1990–1996
227.9
44.7
114.5
415.4
756.1
859.6
599.2
249.4
248.6
250.2
1997–2001
109.8
20.3
131.8
404.5
723.3
818.3
597.0
243.5
242.4
244.6
2002–2006
100.6
16.7
132.3
398.3
723.2
828.3
589.5
241.5
240.7
242.4
2007–2011
154.9
17.1
125.6
369.5
688.5
798.8
546.9
228.7
227.9
229.5
36.4
11.3
86.7
83.4
163.2
323.2
236.6
1968–1970
29.6
22.2
15.3
30.8
32.8
27.3
23.3
22.5
21.4
23.6
1971–1975
47.7
26.0
11.8
25.1
29.1
28.2
16.9
20.4
19.6
21.2
1976–1980
95.0
28.4
10.1
23.1
30.8
35.5
25.5
20.8
20.0
21.6
1981–1985
123.9
28.4
10.7
23.4
37.9
48.3
38.2
22.6
21.7
23.4
1990–1996
25.1
10.8
8.9
23.0
38.9
56.8
45.6
17.0
16.8
17.2
1997–2001
23.9
5.8
9.2
22.7
41.9
57.8
48.1
16.2
16.0
16.5
2002–2006 2007–2011
18.4 29.1
5.2 6.3
9.4 9.0
21.2 19.9
44.1 44.7
64.7 67.5
49.5 49.4
16.1 16.2
15.9 15.9
16.3 16.4
98.3
28.4
58.7
64.4
136.4
247.3
212.4
Male
Rate in 2007–2011 as a percentage of rate in 1968–1970 Female
Rate in 2007–2011 as a percentage of rate in 1968–1970
Discussion
recent years was associated with an increase in obstructed inguinal hernia.
Main findings Interpretation Hospital admission rates for elective repair of inguinal hernia without obstruction in men were reasonably stable, overall, until the mid 2000s when they declined. Overall, admission rates for women with inguinal hernia without obstruction have gradually declined over time. However, there were very substantial differences between the age groups in trends over time. These differences largely ‘cancelled each other out’ at the all ages level, giving the appearance of little change when, in fact, change in some individual age groups has been considerable. There was a decline in admission rates in male infants (though not in female infants). Children aged 1–14, both males and females, experienced a decline in admission rates over time, notably from the mid 1980s. For men with obstructed inguinal hernia, hospital admission rates dropped from the 1960s to the 1980s and then levelled off remaining relatively stable throughout the rest of the study period. There was no evidence that the decline in elective hernia repair in
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Admission rates for elective repair are a product of incidence and prevalence of inguinal hernia, referral to surgical care, and willingness to consider operation by both the patient and the surgeon. The decline in rates of elective repair in male children, and notably in those aged under 1 year, might reflect a decline in the birth prevalence of inguinal hernia. We encourage others, internationally, to study whether there has been a decline in admission rates for inguinal hernia in infants and children, and a decline in the birth prevalence of inguinal hernia, elsewhere. The rise in rates in the elderly may reflect both an increase in occurrence of hernia and increased availability and use (until the most recent years) of surgery for it. We give age-specific and age-standardised rates which take account of the ageing of the population. However, the fact that the population is ageing means that, overall, the
Hernia Table 2 National age- and sexspecific rates of hospital admission episodes for inguinal hernia with obstruction per 100,000 population in each age– sex group, with percentage change comparing the last period with the first
95 % CI \1
1–14
15–44
45–64
65–74
75–84
85?
All
Lower
Upper
1968–1970
171.3
12.7
3.9
14.8
41.6
108.8
227.9
19.1
18.0
20.2
1971–1975
142.5
6.9
2.8
12.9
42.6
99.3
186.1
15.9
15.2
16.7
1976–1980
136.6
5.9
2.5
10.4
37.9
109.2
240.6
15.4
14.6
16.2
1981–1985
137.9
5.6
1.9
11.3
36.0
97.5
216.2
14.6
13.9
15.3
1990–1996
114.7
4.6
2.6
9.6
30.3
78.9
174.0
12.5
12.3
12.6
1997–2001
85.2
3.5
3.0
9.5
31.2
72.3
154.9
11.6
11.4
11.8
2002–2006
68.8
2.6
3.4
9.4
29.8
69.7
141.1
11.0
10.8
11.1
2007–2011
69.9
2.4
3.1
9.6
28.4
66.3
132.3
10.6
10.4
10.8
40.8
18.4
80.6
64.5
68.2
60.9
58.0
1968–1970
3.3
0.3
0.4
2.4
5.4
10.3
17.5
1.8
1.5
2.0
1971–1975
9.3
0.3
0.3
1.7
4.4
13.0
18.0
1.6
1.4
1.9
1976–1980
12.1
0.3
0.2
1.2
3.7
10.0
18.7
1.4
1.2
1.6
1981–1985
14.5
0.4
0.2
1.1
4.3
10.4
16.5
1.5
1.3
1.7
1990–1996
10.5
0.3
0.2
1.0
2.7
7.8
16.9
1.1
1.1
1.2
1997–2001
11.2
0.3
0.2
1.0
2.9
7.5
14.6
1.1
1.1
1.2
2002–2006 2007–2011
8.9 9.9
0.4 0.3
0.2 0.2
0.9 1.0
2.9 3.6
8.5 9.2
16.5 18.6
1.1 1.3
1.1 1.2
1.2 1.3
299.7
100.0
51.2
42.6
67.3
88.7
106.3
With obstruction Male
Rate in 2007–2011 as a percentage of rate in 1968–1970 Female
Rate in 2007–2011 as a percentage of rate in 1968–1970
volume of care for hernia repair in the elderly has gone up more than the age-adjusted rates would indicate. A population-based record linkage study in Denmark, between 2006 and 2010, found that the prevalence of inguinal hernia was highest for those under 5 years old and those between 75 and 80 years old [10]. Previous record linkage studies examining emergent inguinal hernia repair in the Oxford region (1976–1986) and Minnesota (1989–2008) have found a declining trend in repair in males over time [3, 11]. The US research also found a gradual decline of emergent inguinal hernia repair among women [11]. The reason for the decline that we have observed in operation rates for obstructed hernia is unclear. However, a likely explanation is that an increase in the repair of unobstructed hernia in older men—the increase we have observed as a trend over time in operation rates on older men—has led to a reduced ‘prevalence pool’ of men with hernia at risk of obstruction. The decline in recent years in the rate of inguinal hernia without obstruction in males may be a result of a change in clinical guidelines following publication of new clinical evidence [9]. In 2006, a randomised control trial in the US provided evidence for observance, rather than surgical repair, of inguinal hernia
in men who are minimally symptomatic [12]. This evidence was incorporated into policy in England in 2006 [8].
Strengths and weaknesses We provide data on trends in inguinal hernia with and without obstruction over a five-decade period, using the longest runs of English statistics available. The study is reliant on the accuracy of clinical coding. Data on accuracy are not readily available; but the data collection systems for the ORLS and HIPE, covering the early decades of the study, were independent of each other; and the rates in each dataset are similar and they corroborate one another. Our results do not include inguinal hernia repair that was treated privately, and our study would have underestimated the true number of admissions. Data on the number of hernia operations undertaken in private non-NHS facilities in England are not available. Most non-NHS care will be used by people who are covered by private health insurance. The percentage of the UK population covered by private health insurance is small but rising: it was 3.2 % in 1968 and 10.6 % in 2006 (it peaked at 11.7 % in 2000). [3]
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Hernia
It seems unlikely that this modest increase will have impacted much on the large changes seen in our data within individual age groups. Insofar as it may have contributed, its effect would be that the large increases in elective operation rates in the elderly would have been underestimated by our data. Private care, rather than NHS care, is uncommonly used for children or for emergency treatment. Day case care was not included in routine national statistics from 1968 to 1989, although it was included in the Oxford data from its inception and in national statistics from 1990 to 2011. The fact that there was no abrupt increase in the rates in England in 1990, when day cases began to be captured in English HES, suggests that moves from inpatient to day case care did not impact on the overall (day case plus inpatient) rates.
Conclusion Over the past five decades, operation rates for inguinal hernia without obstruction have been largely stable over time, but with big differences between age groups and between males and females. The rate of admission of children has declined substantially over time. The rate of admission for men over 65 has increased substantially over time. There was a large decline in admissions and operations for obstructed inguinal hernia in the 1960s and 1970s in adult males, with a further but smaller decline since then in men aged over 65. Admissions for obstructed hernia have not risen recently, following the recent decline in elective surgery, but this should be monitored in future. Acknowledgments The Unit of Health-Care Epidemiology was funded by the English National Institute for Health Research to build the datasets (grant number RNC/035/02). MJG is part-funded by Public Health England. The views expressed in this paper do not necessarily reflect those of the funding bodies. Conflict of interest The authors declare no conflicts of interest. This was an independent study; the funding source had no involvement in the study design, data collection, data analysis and interpretation, writing of the report, or the decision to submit the article for publication. The views expressed are not necessarily those of the funding body.
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Ethical Standards Ethical approval for a multi-purpose programme of work analyzing these anonymised datasets was obtained from the UK National Research Ethics Service (04/Q2006/176).
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