Table 2.
Multivariable logistic regression analysis of factors associated with the clinical severity of scrub typhus according to the APACHE II score ≥ 10*
| Variable | OR (95% CI) | P | |
|---|---|---|---|
| Factors predisposing for severity | |||
| Age | 1.07 (1.02–1.12) | 0.003 | |
| Diabetes mellitus | 5.55 (1.12–27.48) | 0.036 | |
| Hypertension | 2.08 (0.66–6.56) | 0.211 | |
| Other less frequent chronic diseases† | 3.65 (1.05–12.71) | 0.042 | |
| Visit without diagnosis‡ | 0.32 (0.11–0.93) | 0.036 | |
| Serum OPN (> 100 ng/mL) | 3.35 (1.16–9.69) | 0.026 | |
| Laboratory markers indicating current severity | |||
| Serum OPN (> 100 ng/mL) | 2.96 (1.09–8.04) | 0.034 | |
| Hemoglobin (≤ 10 g/dL) | 32.08 (2.61–393.87) | 0.007 | |
| Platelets (≤ 100,000/mm3) | 1.45 (0.49–4.26) | 0.499 | |
| Serum albumin (≤ 3.0 g/dL) | 1.61 (0.49–5.32) | 0.435 | |
| CRP (> 10 mg/dL) | 3.47 (1.18–10.16) | 0.023 | |
| Serum Cr > 2.0 mg/dL | 6.98 (0.28–174.71) | 0.237 | |
| AST > 40 IU/L | 2.01 (0.23–17.62) | 0.528 | |
| ALT > 40 IU/L | 1.07 (0.24–4.66) | 0.934 | |
| Potassium ≤ 3.5 mmol/L | 1.51 (0.50–4.57) | 0.468 | |
*
OR = odds ratio; CI = confidence interval; OPN = serum osteopontin; CRP = C-reactive protein; AST = aspartate aminotransferase; ALT = alanine aminotransferase.
†
“Other less frequent chronic diseases” include congestive heart failure, cerebrovascular disease, chronic liver disease, asthma, and chronic obstructive pulmonary disease.
‡
Patients who visited the hospital by themselves or who were referred from primary hospitals without initial clinical suspicion of scrub typhus.