The study cohort included 4,379 individuals, of which 3,379 (77.2%) were male, with an average age of 65.2 years (SD 14.7) at their initial gout hospitalisation. Common comorbidities within the cohort included cardiovascular disease (n=2,710, 61.9%), renal failure (n=1,080, 24.7%), diabetes (n=1,106, 25.3%), mental health disorders (n=879, 20.1%), cancer (n=593, 13.5%) and chronic lower respiratory disease (n=559, 12.8%).
In the five years following their initial gout hospital admission, there was 22,222 ED attendances with a median cost of $1,826 per patient (IQR: $433 - $4,414), and 22,452 hospital admissions, with a median cost of $24,254 per patient (IQR: $6,542 - $58,673) (Table 1). Gout was not a major driver of ED or hospital events, with 341 (1.5%) ED attendances and 620 (2.8%) hospital admission with a primary diagnosis of gout.
Table 1
Univariable incident risk ratio (95% confidence intervals) for factors associate with health service utilisation in the five years following initial gout hospitalisation.
| ED presentations | Hospital admissions |
| All presentations | PPE | Cost | All presentations | PPE | Cost |
Age at 1st presentation | 1.00 (1.00, 1.00) | 0.96 (0.96, 0.97) | 1.01 (1.01, 1.02) | 1.03 (1.02, 1.03) | 1.04 (1.03, 1.04) | 1.03 (1.02, 1.03) |
Year of 1st presentation | 1.01 (0.99, 1.03) | 0.88 (0.84, 0.92) | 1.02 (0.99, 1.05) | 1.00 (0.98, 1.01) | 0.95 (0.92, 0.98) | 0.99 (0.97, 1.02) |
Sex (base: male) | 1.32 (1.19, 1.45) | 1.22 (0.97, 1.51) | 1.28 (1.11, 1.49) | 1.28 (1.18, 1.39) | 1.60 (1.36, 1.89) | 1.26 (1.10, 1.45) |
Aboriginality | 3.47 (2.99, 4.03) | 12.98 (9.80, 17.20) | 2.34 (1.75, 2.86) | 1.05 (0.91, 1.21) | 1.39 (1.07, 1.80) | 0.93 (0.74, 1.18) |
Socio-economic status (SES) | | | | | | |
- 0 to 20% (lowest SES) | Base | Base | Base | Base | Base | Base |
- 21 to 40% | 0.53 (0.44, 0.65) | 0.29 (0.21, 0.42) | 0.68 (0.50, 0.92) | 0.92 (0.77, 1.10) | 1.03 (0.74, 1.44) | 0.99 (0.75, 1.31) |
- 41 to 60% | 0.45 (0.38, 0.53) | 0.10 (0.07, 0.14) | 0.70 (0.54, 0.93) | 1.04 (0.89, 1.22) | 1.06 (0.78, 1.44) | 1.22 (0.95, 1.57) |
- 61 to 80% | 0.37 (0.31, 0.45) | 0.10 (0.07, 0.14) | 0.56 (0.42, 0.75) | 0.89 (0.75, 1.05) | 0.97 (0.71, 1.33) | 1.06 (0.81, 1.38) |
- 81 to 100% (highest SES) | 0.27 (0.23, 0.33) | 0.02 (0.01, 0.03) | 0.48 (0.36, 0.64) | 1.02 (0.86, 1.21) | 0.85 (0.62, 1.17) | 1.25 (0.95, 1.63) |
Smoking (ever) | 1.79 (1.64, 1.95) | 1.78 (1.46, 2.16) | 1.68 (1.48, 1.92) | 1.64 (1.52, 1.77) | 2.12 (1.82, 2.46) | 1.48 (1.31, 1.67) |
Comorbidities | | | | | | |
- CVD | 1.87 (1.71, 2.03) | 0.87 (0.72, 1.06) | 2.37 (2.09, 2.69) | 2.32 (2.16, 2.49) | 6.60 (5.71, 7.64) | 2.63 (2.34, 2.96) |
- Renal failure | 1.75 (1.59, 1.93) | 0.53 (0.42, 0.66) | 2.08 (1.81, 2.40) | 2.17 (2.00, 2.35) | 3.96 (3.42, 4.59) | 2.44 (2.14, 2.79) |
- Diabetes | 1.74 (1.59, 1.92) | 1.39 (1.12, 1.71) | 1.83 (1.59, 2.11) | 1.72 (1.59, 1.87) | 4.02 (3.48, 4.64) | 1.76 (1.54, 2.01) |
- Mental health | 2.07 (1.88, 2.29) | 2.49 (2.00, 3.11) | 1.81 (1.55, 2.12) | 1.47 (1.35, 1.61) | 1.71 (1.44, 2.04) | 1.35 (1.17, 1.56) |
- Cancer | 1.14 (1.00, 1.29) | 0.53 (0.40, 0.72) | 1.34 (1.12, 1.61) | 2.04 (1.84, 2.26) | 1.06 (0.86, 1.32) | 2.17 (1.83, 2.57) |
- Chronic lower resp inf | 2.04 (1.81, 2.31) | 1.45 (1.10, 1.92) | 2.08 (1.73, 2.51) | 1.95 (1.75, 2.19) | 4.11 (3.42, 4.95) | 1.83 (1.53, 2.17) |
During the 5 years of follow-up, readmission rates were high, with 3,777 (86.3%) patients returning to hospital within the five-year period. Common primary causes of hospital admissions following the index event were cardiovascular disease (n=3,332, 14.8%), diseases of the digestive tract (n=2,150, 9.6%), diseases of the musculoskeletal and connective tissue (excluding gout) (n=1,771, 7.9%), cancer (n=1,616, 7.2%), respiratory diseases (n=1,627, 7.3%).
During follow-up, 4,059 (18.3%) of ED and 3,834 (17.1%) of hospital admissions were deemed potentially preventable. Of the PPH, 83.5% (n=3,202) were associated with chronic diseases, while 2.6% (n=579) were associated with acute diseases and 1.9% were associated with vaccine preventable diseases.
Factors association with health care utilisation and cost
In the univariable analysis, increased socio-economic status was associated with a reduction in ED attendances, however, this was not reflected in hospital admissions. Smoking was also associated with increased likelihood of hospital and ED, attendances (including PPE) and costs. Findings were similar in the multivariable analysis (Table 2).
Table 2
Multivariable incident risk ratio (95% confidence intervals) for factors associate with health service utilisation in the five years following initial gout hospitalisation.
| ED presentations | Hospital admissions |
| All presentations | PPE | Cost | All presentations | PPE | Cost |
Age at 1st presentation | 1.01 (1.00, 1.01) | 1.00 (0.99, 1.00) | 1.01 (1.00, 1.02) | 1.02 (1.01, 1.02) | 1.02 (1.01, 1.03) | 1.02 (1.02, 1.03) |
Year of 1st presentation | 1.01 (0.99, 1.02) | 0.90 (0.86, 0.94) | 1.02 (0.99, 1.05) | 1.00 (0.98, 1.01) | 0.95 (0.91, 0.98) | 0.98 (0.95, 1.01) |
Sex (base: male) | 1.12 (1.02, 1.23) | 0.86 (0.66, 1.12) | 1.13 (0.97, 1.31) | 1.20 (1.11, 1.30) | 1.14 (0.93, 1.40) | 1.23 (1.07, 1.41) |
Aboriginality | 3.27 (2.80, 3.83) | 2.03 (1.47, 2.80) | 2.96 (2.25, 3.89) | 1.47 (1.27, 1.69) | 0.89 (0.60, 1.34) | 1.46 (1.13, 1.87) |
Socio-economic status (SES) | | | | | | |
- 0 to 20% (lowest SES) | Base | Base | Base | Base | Base | Base |
- 21 to 40% | 0.74 (0.62, 0.88) | 0.68 (0.49, 0.94) | 0.86 (0.64, 1.16) | 0.97 (0.83, 1.13) | 1.14 (0.73, 1.78) | 1.01 (0.77, 1.33) |
- 41 to 60% | 0.64 (0.55, 0.76) | 0.44 (0.32, 0.61) | 0.84 (0.64, 1.12) | 1.06 (0.92, 1.23) | 0.92 (0.60, 1.41) | 1.19 (0.92, 1.54) |
- 61 to 80% | 0.51 (0.43, 0.60) | 0.34 (0.24, 0.49) | 0.66 (0.50, 0.88) | 0.91 (0.79, 1.06) | 0.92 (0.59, 1.42) | 1.05 (0.81, 1.36) |
- 81 to 100% (highest SES) | 0.42 (0.35, 0.50) | 0.14 (0.08, 0.22) | 0.61 (0.45, 0.81) | 1.03 (0.88, 1.20) | 0.92 (0.59, 1.45) | 1.25 (0.95, 1.64) |
Smoking (ever) | 1.42 (1.31, 1.54) | 1.12 (0.89, 1.40) | 1.48 (1.30, 1.68) | 1.46 (1.36, 1.57) | 1.18 (0.96, 1.44) | 1.43 (1.27, 1.61) |
Comorbidities | | | | | | |
- CVD | 1.38 (1.26, 1.51) | 0.92 (0.73, 1.17) | 1.50 (1.30, 1.73) | 1.36 (1.26, 1.47) | 1.78 (1.37, 2.33) | 1.50 (1.32, 1.71) |
- Renal failure | 1.53 (1.39, 1.51) | 0.62 (0.44, 0.88) | 1.73 (1.49, 2.01) | 1.60 (1.48, 1.73) | 1.62 (1.34, 1.96) | 2.10 (1.83, 2.41) |
- Diabetes | 1.20 (1.09, 1.31) | 1.02 (0.78, 1.33) | 1.19 (1.03, 1.38) | 1.21 (1.12, 1.31) | 2.05 (1.70, 2.47) | 1.24 (1.08, 1.42) |
- Mental health | 1.54 (1.40, 1.69) | 0.95 (0.73, 1.24) | 1.52 (1.31, 1.78) | 1.23 (1.14, 1.34) | 1.14 (0.92, 1.40) | 1.23 (1.07, 1.42) |
- Cancer | 1.21 (1.08, 1.36) | 1.10 (0.77, 1.57) | 1.48 (1.24, 1.76) | 1.90 (1.73, 2.09) | 0.64 (0.47, 0.87) | 2.45 (2.08, 2.87) |
- Chronic lower resp inf | 1.32 (1.18, 1.48) | 0.61 (0.40, 0.94) | 1.38 (1.24, 1.76) | 1.27 (1.15, 1.40) | 1.73 (1.39, 2.15) | 1.26 (1.06, 1.49) |