Delay to diagnosis in childhood bone and joint infection.

Aim: To determine the proportion of delayed diagnosis among cases of acute childhood bone and joint infection (BJI) and examine the impact of delayed diagnosis on illness trajectory.

Methods: A retrospective review was undertaken of patients <16 years with acute haematogenous osteomyelitis (AHO) or septic arthritis (SA) treated in the Auckland region from 2018-2023. Electronic case information was used to identify any alternative diagnosis given prior to identification of BJI (delayed disease recognition). Cases were grouped into the following subtypes: multifocal sepsis or shock, "isolated" AHO or SA, or contiguous local infection such as pyomyositis and subperiosteal abscess. Primary outcomes included length of stay (LOS) and hospitalisation cost.

Results: A total of 563 cases of childhood BJI were identified, of whom 512 had clearly documented presenting complaint. A high proportion received an alternative initial diagnosis (43%). Alternatively diagnosed children were more likely to have attended primary or urgent care (82% vs 38%, p=0.00001) and have a recent viral illness (46% vs 34%, p=0.008). Receiving alternative diagnosis was associated with greater delay to treatment (7.8 vs 4 days, p=<0.00001). Contiguous local infection was more likely in children with >1 week of symptoms (34% vs 17%, p=0.002). Contiguous infection required more surgical intervention, longer LOS and higher hospitalisation cost when compared to isolated AHO.

Conclusion: Delayed recognition of childhood AHO and SA is common and is associated with delayed treatment. Symptoms present for >1 week are associated with contiguous infection, which, compared with isolated AHO, requires more surgery with increased hospitalisation costs.