Elsevier

Journal of Infection

Volume 68, Issue 4, April 2014, Pages 313-320
Journal of Infection

Increasing incidence of pyogenic spondylodiscitis: A 14-year population-based study

https://doi.org/10.1016/j.jinf.2013.11.011Get rights and content

Summary

Objectives

Smaller studies indicate that the incidence of pyogenic spondylodiscitis is increasing, possible related to a growing elderly population. Data supporting this is sparse, and we therefore studied patient characteristics and changes in spondylodiscitis incidence 1995–2008.

Methods

In a population-based study we identified all patients aged ≥18 years treated for pyogenic spondylodiscitis in Funen County, Denmark (population 483 123). Annual incidences were determined. Demographics, symptoms and diagnostic methods were recorded.

Results

We found 192 cases: median age 66.6 years; 57.3% men; 76.6% culture positive cases. Staphylococcus aureus was the most common pathogen (55.1%). During 1995–2008 the overall incidence, incidence of culture negative cases, and incidence of cases due to S. aureus increased 2.2–5.8, 0.3–1.8, and 1.6–2.5 cases per 100 000 person years, respectively. The elderly had the highest incidence compared to those aged ≤70 years (rate ratio for men 5.9 (95% CI: 4.2–8.5) and for women 3.5 (95% CI: 2.3–5.3)).

Conclusions

During 1995–2008 the overall incidence of S. aureus and culture negative cases of spondylodiscitis increased and remained highest among the elderly. Whether the increase is real or is a result of improved diagnostic methods and workup remains unknown.

Introduction

Pyogenic spondylodiscitis remains a diagnostic challenge, and affected patients are at risk of permanent neurological deficits and chronic pain.1, 2, 3 Newer data suggest that treatment with antibiotics for a period of 6 weeks are as effective as treatment for 12 weeks; but the general recommendation has until recently been towards the need of long-term treatment.4, 5

The incidence rate of non-tuberculosis non-postoperative spondylodiscitis has previously been estimated to 2.2–2.4 cases per 100 000 person years,6, 7 and it has been reported to be increasing mainly due to an increase in culture negative cases8 and due to the increasing elderly population.9 The influence of age was highlighted in a study from 2009, where Hutchinson et al. found an incidence rate of 9.8 cases per 100 000 person years for the population over 65 years of age.10

The diagnosis is based on symptoms, clinical findings, and imaging and laboratory results. Nowadays, MRI is the main radiological examination and considered to be the gold standard imaging method.11, 12 Before MRI became widely available plain x-ray as well as leucocyte- and bone scintigraphy were used as diagnostic methods.13

The time from onset of symptoms to diagnosis is often long14, 15 probably due to lack of awareness and the often non-specific nature of symptoms.3, 16, 17

Most publications concerning spondylodiscitis are small with less than one-hundred cases. We report data from a larger population-based study describing changes in incidence rates as well as patient characteristics and clinical findings of pyogenic spondylodiscitis over 14 years.

Section snippets

Case identification and study population

We conducted a population-based study using the Funen County Patient Administrative System (FPAS) to identify all patients discharged with a diagnosis of spinal infection (including diagnosis of epidural abscesses, vertebral osteomyelitis, and discitis) during January 1994–May 2009 in Funen County, Denmark (population of 483 123 June 1, 200818). We identified patients with relevant discharge codes using the International Disease Classification coding system 10th edition (ICD-10) (A02.2; A18;

Results

We identified 1386 potential cases of pyogenic spondylodiscitis based on relevant discharge codes, and 192 of these met our case definition criteria and were included in the study (see Fig. 1).

The median age was 66.6 years (IQR: 56.2–75.6), 57.3% (110/192) were men.

Discussion

In this population-based study describing the characteristics of adult patients with pyogenic non-tuberculosis spondylodiscitis, we found that the overall incidence rate increased considerably during 1995–2008 and that the disease was the most common among the elderly with a higher incidence among men. This sex difference is in agreement with findings from other previous studies.9, 23 The reason for the higher incidence among men is not known with certainty, but it may be of importance that men

Acknowledgments

This work was supported by the Else Poulsen Mindelegat, the Region of Southern Denmark Research Grant and the University of Southern Denmark Research Grant.

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