# Factors associated with diagnostic delay and prognosis in hospitalized patients with strongyloidiasis in Okinawa, Japan

## TL;DR

The study finds that delayed diagnosis of strongyloidiasis in elderly patients in Okinawa is linked to higher mortality and worse outcomes.

## Contribution

The study identifies factors associated with diagnostic delay and prognosis in strongyloidiasis patients, emphasizing the risk of relying on eosinophilia for diagnosis.

## Key findings

- Delayed diagnosis of strongyloidiasis is significantly associated with higher in-hospital mortality.
- Patients with delayed diagnosis tend to be older, have lower hemoglobin, and lack eosinophilia.
- Absence of eosinophilia can lead to missed diagnoses, especially in elderly patients.

## Abstract

Prognosis and factors correlated to diagnostic delays in patients with strongyloidiasis, a parasitic disease, remain poorly understood. This study investigated the relationship among diagnostic delay, prognosis, and eosinophilia in patients with strongyloidiasis.

Hospitalized patients with a confirmed diagnosis of strongyloidiasis at a single hospital over 10 years (2013–2023) were retrospectively screened. Fifty-five inpatients were included (median age, 81 years); 34 patients (61.8%) were male, and all but one patient was born in Okinawa before 1960. Duration from onset of symptoms to diagnosis was 10 days (median), hospitalization length was 37 days (median), and eight patients (14.5%) died. We classified diagnoses made after ≥30 days as delayed diagnosis and compared the patients with and without delayed diagnosis. Patients with delayed diagnosis had more in-hospital deaths than their counterparts (55.6% versus [vs.] 7.1%, P < 0.005). Compared with patients diagnosed earlier, those with delayed diagnosis were also characterized by older age (90 vs. 78.5 years, P < 0.005), more frequent fever (55.6% vs. 19.6%, P = 0.037), lower hemoglobin levels (10.1 vs. 11.8 g/dL, P = 0.0363), absence of eosinophilia (0% vs. 22%, P = 0.015), higher rates of sepsis (50% vs. 10.7%, P = 0.03), and prolonged hospitalization (77 vs. 23.5 days, P < 0.005). Diagnostic delay even after adjusting for age and sex using multivariate logistic regression analyses was a significant risk factor for mortality (odds ratio = 11.3, P = 0.022). Patients without eosinophilia were older than those with eosinophilia (84.5 vs. 76 years, P = 0.005) and not associated with in-hospital death (23.3% vs. 4.8%, P = 0.118).

Diagnostic delays are associated with a poor prognosis of strongyloidiasis. The absence of eosinophilia led to overlooked diagnoses. Screening should be considered before starting immunosuppressive therapy; relying on eosinophil counts could delay diagnosis.

Strongyloidiasis, a parasitic disease transmitted percutaneously from soil, mainly affects the small intestine. Diagnostic delays may worsen prognosis because the disease can become severe in immunosuppressed hosts, resulting in disseminated strongyloidiasis or hyperinfection. However, few studies have investigated the diagnostic delay associated with strongyloidiasis. This study examined the relationship between diagnostic delay and strongyloidiasis prognosis as well as factors associated with diagnostic delay at a single general hospital in Okinawa Prefecture, Japan. Fifty-five inpatients with strongyloidiasis were included from 2013 to 2023.

Patients with strongyloidiasis diagnosed in ≥30 days showed more frequent in-hospital deaths (55.6% versus [vs.] 19.6%, P = 0.037), more frequent sepsis, and longer hospital stays with the characteristics of older age (median age: 86.5), anemia, and normal eosinophil counts compared with those diagnosed in <30 days. Patients without eosinophilia were older than those with eosinophilia (76 vs. 84.5 years, P = 0.005). Strongyloidiasis should be considered in older individuals from endemic areas even if blood eosinophil counts are normal. In Japan, patients born before 1960 are screened for strongyloidiasis.