{'fraction_non_alphanumeric': 0.03673938002296211, 'fraction_numerical': 0.03176425564485266, 'mean_word_length': 5.165094339622642, 'pattern_counts': {'":': 0, '<': 2, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The effect of environmental factors on the incidence of perforated appendicitis.

BACKGROUND
Acute appendicitis is the most common abdominal emergency. Its etiopathogenesis appears to be multifactorial. Several studies suggested a relationship between the development of acute appendicitis and some environmental factors. Air pollution predisposes some people to develop perforated appendicitis. However, data are relatively scarce and the results still controversial.


AIM
Determine the seasonal variation of acute appendicitis and study the association between perforated appendicitis and short-term exposure to climatic factors and to air pollutants.


METHODS
A cross-sectional study was conducted including patients hospitalized in the general surgery department of Farhat Hached University Hospital in Sousse for acute appendicitis between January 1st and December 31st, 2014. Climatic conditions were collected from the National Institute of Meteorology. Data on air pollution were given by the National Agency for the Protection of the Environment and obtained by the modeling of the atmospheric pollution. For statistical analysis, we used mean concentrations of each environmental factor corresponding to the day of hospital admission and lagged by the 7 previous days. These factors were compared between the group of patients with perforated appendicitis and patients with nonperforated appendicitis.


RESULTS
We collected 246 cases of acute appendicitis. Perforated appendicitis was reported in 15.2% of the cases. The incidence of acute appendicitis was higher during summer. Compared to nonperforated appendicitis, perforated appendicitis was significantly associated with the mean relative humidity of the 5 day lag (p = 0.046), rainfall of the 7 day lag (p = 0.043), and consultation delay (p <10-3). Furthermore, perforated appendicitis was significantly associated with the daily mean concentration of carbon dioxide (p = 0.042), the 2- day lag mean concentration of particulate matter less than 10 μ (PM10 ) (p = 0.016), and the 2-day lag mean concentration of ozone (p = 0.048). After multivariate statistical analysis, predictive factors for perforated appendicitis were the consultation delay (OR: 1.621, 95% CI [1.288 - 2.039]; p<10-3) and the 2 day lag mean concentration of PM10 (OR: 1.066, 95% CI [1.007- 1.130]; p = 0.029).


CONCLUSION
Short-term exposure to particulate matter was associated with perforated appendicitis. Further large-scale studies are needed to support this conclusion.


KEY WORDS
Air pollution, Appendicitis, perforated appendicitis, Climateparticulate matter.