Impact of type 2 diabetes mellitus on interstitial lung disease risk in rheumatoid arthritis

Table 1 Baseline characteristics before matching, n (%)/mean ± SD

Baseline characteristics	RA+DM (n = 60523)	RA-DM (n = 138848)	P value
Age	69.06 (11.56)	68.25 (14.41)	< 0.001
Gender
Female	42031 (69.45)	102277 (73.66)	< 0.001
Race
White	40840 (67.48)	108904 (78.43)	< 0.001
Black	10059 (16.62)	14765 (10.63)	< 0.001
Hispanic	6368 (10.52)	9481 (6.83)	< 0.001
Asian	1375 (2.27)	2718 (1.96)	< 0.001
Native	1196 (1.98)	1999 (1.44)	< 0.001
Other	685 (1.13)	990 (0.71)	< 0.001
Comorbidities
Gastro-esophageal reflux disease	21363 (35.3)	46663 (33.61)	< 0.001
Chronic obstructive pulmonary disease	7849 (12.97)	16699 (12.03)	< 0.001
Asthma	6271 (10.36)	12672 (9.13)	< 0.001
Smoking	5780 (9.55)	15831 (11.4)	< 0.001
Heart failure	29061 (48.02)	38053 (27.4)	< 0.001
Chronic kidney disease	20373 (33.66)	23650 (17.03)	< 0.001
Atrial fibrillation	9868 (16.3)	19183 (13.81)	< 0.001
Ventricular tachycardia	1065 (1.76)	1996 (1.44)	< 0.001
Hypertension	53568 (88.51)	99210 (71.45)	< 0.001
Obesity	19604 (32.39)	25059 (18.05)	< 0.001
Alcohol use	1132 (1.87)	4936 (3.55)	< 0.001
Steroids use	5767 (9.53)	15274 (11.0)	< 0.001
Coronary artery disease	21901 (36.19)	31360 (22.58)	< 0.001

RA: Rheumatoid arthritis; DM: Diabetes mellitus.

Table 2 Baseline characteristics after matching, n (%)/mean ± SD

Baseline characteristics	RA+DM (n = 60523)	RA-DM (n = 60523)	P value
Age	69.06 (11.56)	69.1 (11.60)	0.986
Gender
Female	42031 (69.45)	41985 (69.37)	0.774
Race
White	40840 (67.48)	40910 (67.59)	0.667
Black	10059 (16.62)	9997 (16.51)	0.632
Hispanic	6368 (10.52)	6391 (10.55)	0.830
Asian	1375 (2.27)	1384 (2.28)	0.862
Native	1196 (1.98)	1149 (1.89)	0.327
Other	685 (1.13)	692 (1.14)	0.850
Comorbidities
Gastro-esophageal reflux disease	21363 (35.30)	21363 (35.30)	1.000
Chronic obstructive pulmonary disease	7849 (12.97)	7833 (12.94)	0.898
Asthma	6271 (10.36)	6268 (10.36)	0.985
Smoking	5780 (9.55)	5761 (9.52)	0.860
Heart failure	29061 (48.02)	29049 (48.00)	0.950
Chronic kidney disease	20373 (33.66)	20348 (33.62)	0.884
Atrial fibrillation	9868 (16.30)	9863 (16.30)	0.975
Ventricular tachycardia	1065 (1.76)	1059 (1.75)	0.913
Hypertension	53568 (88.51)	53525 (88.44)	0.705
Obesity	19604 (32.39)	19580 (32.35)	0.888
Alcohol use	1132 (1.87)	1129 (1.87)	0.966
Steroids use	5767 (9.53)	5760 (9.52)	0.953
Coronary artery disease	21901 (36.19)	21890 (36.17)	0.952

RA: Rheumatoid arthritis; DM: Diabetes mellitus.

Table 3 Primary outcomes after propensity matching, n (%)

Outcomes	RA+DM (n = 50423)	RA-DM (n = 50423)	P value
Interstitial lung diseases	1360 (2.25)	672 (1.11)	< 0.001
Usual interstitial pneumonia/pulmonary fibrosis	840 (1.67)	227 (0.45)	< 0.001
Non-specific interstitial pneumonia	494 (0.98)	133 (0.26)	< 0.001
Eosinophilic lung disease	18 (0.04)	78 (0.15)	< 0.001
Respiratory bronchiolitis interstitial lung disease	8 (0.02)	5 (0.01)	< 0.001
Cryptogenic organizing pneumonia	17 (0.03)	1 (< 0.01)	0.057
Acute interstitial pneumonitis	11 (0.02)	5 (0.01)	< 0.001

RA: Rheumatoid arthritis; DM: Diabetes mellitus.

Table 4 Primary and secondary outcomes odds ratio after multivariate regression

Outcomes	Odds ratio	P value	95%CI
Interstitial lung diseases	2.203	< 0.001	1.843-2.219
Usual interstitial pneumonia/pulmonary fibrosis	3.200	< 0.001	2.800-3.700
Non-specific interstitial pneumonia	3.500	< 0.001	2.900-4.100
Eosinophilic lung disease	0.232	< 0.001	0.112-0.415
Respiratory bronchiolitis interstitial lung disease	1.636	0.002	0.531-5.036
Cryptogenic organizing pneumonia	96.040	0.06	0.860-1072
Acute interstitial pneumonitis	2.201	< 0.001	0.764-6.335
Acute respiratory distress syndrome	1.116	0.260	0.921-1.353
Pneumothorax	1.848	< 0.001	1.465-2.332
Pleural effusion	1.028	0.49	0.959-1.101
Pulmonary arterial hypertension	1.397	< 0.001	1.331-1.467

Table 5 Secondary outcomes after propensity matching, n (%)

Outcomes	RA+DM (n = 50423)	RA-DM (n = 50423)	P value
Acute respiratory distress syndrome	221 (0.44)	198 (0.39)	0.260
Pneumothorax	203 (0.40)	110 (0.22)	< 0.001
Pleural effusion	1694 (3.36)	1648 (3.27)	0.49
Pulmonary arterial hypertension	4141 (8.21)	2964 (5.88)	< 0.001

RA: Rheumatoid arthritis; DM: Diabetes mellitus.