Table 1. Multivariate logistic regression of dengue fever versus chikungunya infection (Table 1a); and dengue hemorrhagic fever versus chikungunya (Table 1b) at presentation among in-patients Tan Tock Seng Hospital, Singapore.

Table 1a
Variable	aOR	95% CI		p
Tachycardia (pulse>100/minute)	0.0029	0.00016	0.036	<0.0001
Cough	0.067	0.0052	0.59	0.012
Fever at presentation	0.042	0.0003	0.5	0.01
Serum alanine aminotransferase (per 100 units)	0.11	0.014	0.41	0.0001
Anorexia	0.14	0.023	0.67	0.011
Serum hematocrit	0.34	0.18	0.63	0.0003
Serum urea	0.35	0.2	0.57	<0.0001
Duration of fever (days)	0.6	0.39	0.89	0.0098
Serum albumin	0.71	0.6	0.83	<0.0001
Leukocyte count	1.53	1.06	2.22	0.022
Platelet count (per 10 units)	1.61	1.41	1.89	<0.0001
Lymphocyte proportion (per 10 units)	2.1	1.2	3.9	0.0063
Serum creatinine (per 10 units)	2.2	1.5	3.5	<0.0001
Serum bilirubin (per 10 units)	3.7	1.8	8.1	0.0011
Myalgia/arthralgia	13	3	73	0.0003
Hemoglobin	13	2.7	73	0.0013

Estimates are derived using Firth's modified score procedure, and confidence intervals using profile penalised likelihoods, as described in the text. Adjusted odds ratios (aOR) are in favour of chikungunya infection: variables associated with chikungunya are indicated in italic type.