An Unexpected Increase in Adult Appendicitis in England (2000/01 to 2012/13): Could Cytomegalovirus (CMV) be A Risk Factor?

Abstract

Aims: To study the trends in admission for diseases of the appendix and to attempt to present a potential basis for the observed (complex) age-dependent trends and etiologies. Study Design: Longitudinal study of admissions relating to the appendix with analysis by age and gender. Place and Duration of Study: Admissions for diseases affecting the appendix for the residents of England over the period 2000/01 to 2012/13. Methodology: Retrospective application of age-standardized admission rates based on 2012/13 as the base year to determine what proportion of the increase in admissions is due to demography or to non-demographic forces. Synthesis of available literature covering diseases of the appendix to propose possible causes for the increase in admissions. Results: Based on admissions in 2012/13 diseases of the appendix cost the NHS in England around £107 million per annum (roughly £2 per head of population per annum). Admission rates peak at age 17 but have been increasing over the past 14 years in adults but not children. The rate of increase escalates with age and is more rapid in females. The trend for females shows far higher volatility than that for males and both show some degree of cyclic behavior. Depending on age, demographic change can only explain between 20% and 40% of the long-term increase. Social and health service factors are unlikely to explain this gap. Conclusion: An immune/infectious basis for increasing admission rates appears most likely. A possible role for the immune modulating herpes virus, cytomegalovirus (CMV), is discussed in the context of a potential linkage between infection with multiple agents (called the infectious burden) and the development of multiple morbidity. Both of which increase with age and are amenable to manipulation by CMV. The suggested mechanism may also provide insight into why the rates for admission of certain medical diagnoses are increasing far faster than due to demographic change.