Abstract
Social disparities in chronic kidney disease (CKD) are a reality. Low socioeconomic status is associated with an increased incidence of CKD and overall worse outcomes. In Portugal, similarly to many European countries, a National Health System (NHS) was established to provide equity in healthcare access, but its impact in specialized CKD care is unclear. This study aims to compare the effects of economic insufficiency in referral and overall specialized kidney care in a Portuguese centre.
Retrospective cohort study evaluating maintenance haemodialysis patients of a Public Portuguese Nephrology Centre from 2017 through 2021. Medical records were compared for the presence of Low-Income status (LIs), with primary outcome as baseline estimated glomerular filtration rate (eGFR) at nephrology referral and secondary outcomes as presence of kidney replacement therapy options appointment (KRTOa), timely vascular access assessment and time to dialysis from referral.
A total of 212 participants were evaluated, 96 with LIs. This group presented higher sCr and lower eGFR at referral (2.35 versus 3.29 mg/dL, P < .001; 27.63 versus 18.47 mL/min/1.73 m2 P <.001, respectively). LIs associated with absence of KRTOa {OR: 2.7, [95% confidence interval (95% CI): 1.44–5.08]; P = .003} and late vascular access evaluation (OR: 2.77, 95% CI: 1.55–4.98; P = .001). Dialysis-free survival analysis revealed shorter time to dialysis in the LIs group (15.77 versus 20.71 months; P < .001) with a higher cumulative incidence in dialysis at 24 months (HR: 2.11, 95% CI: 1.39–3.21; P < .001), a difference that was not verified after adjusting for eGFR at referral (HR: 1.16, 95% CI: 0.74–1.80; P = .53).
Low-Income CKD Portuguese patients are at risk of late nephrology referral, an established factor for adverse outcomes. Shorter time to dialysis appears significative in reducing adequate kidney care access, which can be attenuated through education of primary care providers and general population for CKD.
Relevant descriptive and comparative analysis
| LIs | Non-LIs | Statistical analysis | |
|---|---|---|---|
| Gender, female, n (%) | 40 (41.67) | 44 (37.93) | χ2(1) = 0.31, P = .67 |
| Age, mean (σ) | 72.55 (12.96) | 70.77 (11.32) | t(210) = –1.07, P = .29 |
| Diabetes, present, n (%) | 42 (43.75) | 78 (67.24) | χ2(1) = 11.8, P=.001 |
| Primary outcome | |||
| sCr at referral, mean (σ) | 3.29 (1.21) | 2.36 (0.7) | t(210) = –6.76, P<.001 |
| GFR at referral, mean (σ) | 18.47 (7.55) | 27.63 (10.74) | t(210) = 7.29, P<.001 |
| Stage at referral, n (%) | χ2 MH (1) = 33.84, P<.001a | ||
| 3A | 0 | 8 (6.90) | |
| 3B | 8 (8.33) | 30 (25.86) | |
| 4 | 58 (60.42) | 70 (60.34) | |
| 5 | 30 (31.25) | 8 (6.90) | |
| Secondary outcomes | |||
| Presence of KRT options Appointment, n (%) | 46 (48.42) | 81(71.05) | χ2(1) = 11.13, P=.001 OR: 2.64 (1.44–5.08)b |
| Timely vascular access Assessment, n (%) | 51 (53.13) | 88 (75.86) | χ2(1) = 12.03, P=.001 OR: 2.77 (1.55–4.98)b |
| Time to dialysis, mean (σ) | 31.28 (33.34) | 47.83 (35.51) | t(210) = 3.5, P=.001 |
| Total, n | 96 | 116 |
| LIs | Non-LIs | Statistical analysis | |
|---|---|---|---|
| Gender, female, n (%) | 40 (41.67) | 44 (37.93) | χ2(1) = 0.31, P = .67 |
| Age, mean (σ) | 72.55 (12.96) | 70.77 (11.32) | t(210) = –1.07, P = .29 |
| Diabetes, present, n (%) | 42 (43.75) | 78 (67.24) | χ2(1) = 11.8, P=.001 |
| Primary outcome | |||
| sCr at referral, mean (σ) | 3.29 (1.21) | 2.36 (0.7) | t(210) = –6.76, P<.001 |
| GFR at referral, mean (σ) | 18.47 (7.55) | 27.63 (10.74) | t(210) = 7.29, P<.001 |
| Stage at referral, n (%) | χ2 MH (1) = 33.84, P<.001a | ||
| 3A | 0 | 8 (6.90) | |
| 3B | 8 (8.33) | 30 (25.86) | |
| 4 | 58 (60.42) | 70 (60.34) | |
| 5 | 30 (31.25) | 8 (6.90) | |
| Secondary outcomes | |||
| Presence of KRT options Appointment, n (%) | 46 (48.42) | 81(71.05) | χ2(1) = 11.13, P=.001 OR: 2.64 (1.44–5.08)b |
| Timely vascular access Assessment, n (%) | 51 (53.13) | 88 (75.86) | χ2(1) = 12.03, P=.001 OR: 2.77 (1.55–4.98)b |
| Time to dialysis, mean (σ) | 31.28 (33.34) | 47.83 (35.51) | t(210) = 3.5, P=.001 |
| Total, n | 96 | 116 |
aMantel–Haenzsel test for linear trend.
bOdds Ratio is presented as negative outcomes (absence of KRTOa and untimely assessment) for the LIs group, with 95% confidence intervals for.
non-LIs, not Low-Income status; χ2, Chi-squared; σ, Standard deviation; t, t-value for Student's t-test for difference in means; sCr, serum creatinine; GFR, glomerular filtration rate; MH, Mantel–Haenzsel; KRT, kidney replacement therapy.
Relevant descriptive and comparative analysis
| LIs | Non-LIs | Statistical analysis | |
|---|---|---|---|
| Gender, female, n (%) | 40 (41.67) | 44 (37.93) | χ2(1) = 0.31, P = .67 |
| Age, mean (σ) | 72.55 (12.96) | 70.77 (11.32) | t(210) = –1.07, P = .29 |
| Diabetes, present, n (%) | 42 (43.75) | 78 (67.24) | χ2(1) = 11.8, P=.001 |
| Primary outcome | |||
| sCr at referral, mean (σ) | 3.29 (1.21) | 2.36 (0.7) | t(210) = –6.76, P<.001 |
| GFR at referral, mean (σ) | 18.47 (7.55) | 27.63 (10.74) | t(210) = 7.29, P<.001 |
| Stage at referral, n (%) | χ2 MH (1) = 33.84, P<.001a | ||
| 3A | 0 | 8 (6.90) | |
| 3B | 8 (8.33) | 30 (25.86) | |
| 4 | 58 (60.42) | 70 (60.34) | |
| 5 | 30 (31.25) | 8 (6.90) | |
| Secondary outcomes | |||
| Presence of KRT options Appointment, n (%) | 46 (48.42) | 81(71.05) | χ2(1) = 11.13, P=.001 OR: 2.64 (1.44–5.08)b |
| Timely vascular access Assessment, n (%) | 51 (53.13) | 88 (75.86) | χ2(1) = 12.03, P=.001 OR: 2.77 (1.55–4.98)b |
| Time to dialysis, mean (σ) | 31.28 (33.34) | 47.83 (35.51) | t(210) = 3.5, P=.001 |
| Total, n | 96 | 116 |
| LIs | Non-LIs | Statistical analysis | |
|---|---|---|---|
| Gender, female, n (%) | 40 (41.67) | 44 (37.93) | χ2(1) = 0.31, P = .67 |
| Age, mean (σ) | 72.55 (12.96) | 70.77 (11.32) | t(210) = –1.07, P = .29 |
| Diabetes, present, n (%) | 42 (43.75) | 78 (67.24) | χ2(1) = 11.8, P=.001 |
| Primary outcome | |||
| sCr at referral, mean (σ) | 3.29 (1.21) | 2.36 (0.7) | t(210) = –6.76, P<.001 |
| GFR at referral, mean (σ) | 18.47 (7.55) | 27.63 (10.74) | t(210) = 7.29, P<.001 |
| Stage at referral, n (%) | χ2 MH (1) = 33.84, P<.001a | ||
| 3A | 0 | 8 (6.90) | |
| 3B | 8 (8.33) | 30 (25.86) | |
| 4 | 58 (60.42) | 70 (60.34) | |
| 5 | 30 (31.25) | 8 (6.90) | |
| Secondary outcomes | |||
| Presence of KRT options Appointment, n (%) | 46 (48.42) | 81(71.05) | χ2(1) = 11.13, P=.001 OR: 2.64 (1.44–5.08)b |
| Timely vascular access Assessment, n (%) | 51 (53.13) | 88 (75.86) | χ2(1) = 12.03, P=.001 OR: 2.77 (1.55–4.98)b |
| Time to dialysis, mean (σ) | 31.28 (33.34) | 47.83 (35.51) | t(210) = 3.5, P=.001 |
| Total, n | 96 | 116 |
aMantel–Haenzsel test for linear trend.
bOdds Ratio is presented as negative outcomes (absence of KRTOa and untimely assessment) for the LIs group, with 95% confidence intervals for.
non-LIs, not Low-Income status; χ2, Chi-squared; σ, Standard deviation; t, t-value for Student's t-test for difference in means; sCr, serum creatinine; GFR, glomerular filtration rate; MH, Mantel–Haenzsel; KRT, kidney replacement therapy.
Dialysis-free survival analysis at 24 months from referral. (A) Kaplan–Meier estimates plot reveals a higher probability of incident dialysis in the LIs group, corroborated by a statistically significant Log-Rank Test (P < 0.001). (B) Cox Regression reveals an increased cumulative incidence of the LIs. (C) After adjusting for GFR at referral, LIs patients no longer show increased cumulative incidence or a statistically significant hazard ratio for dialysis start.
Comments