Table 3.

Longitudinal estimates of mean per-patient-per-year (PPPY) healthcare costs (US$) using hierarchical generalised linear mixed models

Adjusted cost ratio (95% CI)	Class 2	Class 1	Class 3	Class 4
Total healthcare costs	Reference	1.43 (1.26–1.62)***	1.17 (1.04–1.30)**	1.00 (0.89–1.11)
OPD care costs	Reference	1.41 (1.31–1.52)***	1.16 (1.09–1.24)***	1.07 (1.00–1.14)
Acute care costs	Reference	1.25 (1.11–1.42)***	1.06 (0.95–1.18)	0.96 (0.86–1.07)
HDU care costs	Reference	1.18 (0.83–1.68)	0.90 (0.64–1.26)	1.15 (0.83–1.60)
ICU care costs	Reference	1.54 (1.04–2.29)*	1.37 (0.94–1.99)	1.55 (1.08–2.23)*
Rehabilitation and infirmary care costs	Reference	1.12 (0.93–1.34)	1.02 (0.87–1.21)	0.99 (0.84–1.17)
Psychiatric care costs	Reference	3.30 (1.28–8.47)*	7.41 (3.37–16.27)***	4.72 (1.83–12.23)**
A&E care costs	Reference	1.08 (1.01–1.15)*	1.06 (0.99–1.12)	1.00 (0.94–1.06)

Models were adjusted for alcohol use, family history of diabetes, diastolic BP, plasma albumin, alkaline phosphatase, eGFR, prior severe hypoglycaemia, prior CVD, prior cancer and EQ-5D-3L (mobility, self-care, usual activities, pain/discomfort and anxiety/depression). Psychiatric care cost exhibits high zero-inflation. The model was simplified by including a year-varying random slope only at the individual level, while adjusting for the variables mentioned earlier, except for alcohol use, plasma albumin and alkaline phosphatase

***p<0.001, **p<0.01, *p<0.05

A&E, accident and emergency; CI, confidence interval; CVD, cardiovascular disease; eGFR, estimated glomerular filtration rate; EQ-5D-3L, EuroQol five-dimensional three-level questionnaire; HDU, high-dependency unit; ICU, intensive care unit; OPD, outpatient department