Table 4. Multivariate analysis of overall survival and lung cancer-specific survival in M1a NSCLC patients only due to ipsilateral malignant pleural effusion after propensity score matching.

Variables	Overall survival		Lung cancer-specific survival
	Hazard Ratios (95% CI)	p Value	Hazard Ratios (95% CI)	p Value
Age
≤65 y	1.00 (Reference)		1.00 (Reference)
>65 y	1.063 (0.746-1.515)	0.735	1.013 (0.700-1.465)	0.947
Gender
Female	1.00 (Reference)		1.00 (Reference)
Male	1.233 (0.871-1.745)	0.237	1.226 (0.855-1.758)	0.268
Married
Yes	1.00 (Reference)		1.00 (Reference)
No	1.353 (0.946-1.936)	0.098	1.261 (0.870-1.827)	0.220
Race
White	1.00 (Reference)		1.00 (Reference)
Black	1.056 (0.643-1.733)	0.831	1.087 (0.652-1.812)	0.748
Other	1.254 (0.632-2.488)	0.517	1.187 (0.583-2.419)	0.636
Tumor Size
≤3cm	1.00 (Reference)		1.00 (Reference)
≤5cm	0.670 (0.438-1.024)	0.064	0.622 (0.400-0.968)	0.035
≤7cm	1.157 (0.667-2.007)	0.603	1.048 (0.591-1.856)	0.873
>7cm	0.891 (0.508-1.562)	0.687	0.798 (0.439-1.449)	0.458
Location
Main bronchus	1.00 (Reference)		1.00 (Reference)
Upper	0.706 (0.373-1.339)	0.286	0.724 (0.372-1.407)	0.340
Middle	1.012 (0.440-2.328)	0.977	1.012 (0.425-2.419)	0.976
Lower	0.935 (0.485-1.801)	0.840	0.915 (0.461-1.817)	0.801
Overlap	6.215 (1.159-33.325)	0.033	7.041 (1.279-38.772)	0.025
Lymph node status
N0	1.00 (Reference)		1.00 (Reference)
N1	1.238 (0.726-2.111)	0.434	1.211 (0.686-2.137)	0.510
N2	1.697 (1.144-2.517)	0.009	1.844 (1.225-2.774)	0.003
N3	2.235 (0.871-5.734)	0.094	2.577 (0.991-6.698)	0.052
NX	<0.001	0.966	<0.001	0.968
Histology
Adenocarcinoma	1.00 (Reference)		1.00 (Reference)
Squamous cell carcinoma	0.924 (0.566-1.509)	0.752	1.014 (0.609-1.688)	0.959
Other	1.121 (0.738-1.704)	0.592	1.128 (0.728-1.748)	0.589
Primary tumor resection
Yes	1.00 (Reference)		1.00 (Reference)
No	2.309 (1.636-3.259)	<0.001	2.301 (1.610-3.287)	<0.001
Radiotherapy
Yes	1.00 (Reference)		1.00 (Reference)
No	1.275 (0.816-1.992)	0.286	1.391 (0.868-2.230)	0.170

Bold values corresponds to the comparisons with P < 0.001.