Cardiorenal syndrome in German primary care: real-world diagnostics and SGLT2 Inhibitor use

Background Heart failure (HF) and chronic kidney disease (CKD) frequently coexist within the cardiorenal syndrome and are predominantly managed in primary care. Affected patients face markedly increased risks of morbidity, mortality, and hospitalisation. Although guideline-directed medical therapy (GDMT), particularly sodium–glucose cotransporter 2 inhibitors (SGLT2i), improves cardiovascular and renal outcomes, implementation in routine care in Germany appears limited. Structured, cross-sectoral management is essential, yet real-world evidence from primary care remains scarce. Objective To characterize real-world management of patients with cardiorenal syndrome (HF+CKD) in German primary care, focusing on diagnostics and the use and timing of GDMT—particularly SGLT2i—using anonymised electronic health records. Methods Within the InspeCKD study framework, WATCH-HF 2.1 was a retrospective cross-sectional analysis using anonymised routine data from 1,824 general practices. Adults with documented cardiovascular risk factors or diagnoses, including HF (all phenotypes), were identified via ICD-10. The observation period covered 01/2023-12/2024, with routine documentation and ≥1 year of follow-up (mean 1.71 ± 0.28 years). Outcomes included the prevalence of HF and CKD, documentation of NT-proBNP testing, and SGLT2i use and initiation among patients with HF+CKD. Results Among 982,250 patients in WATCH 2.1, 68,672 (7.0%) had HF; 4,487 (6.5%) had documented CKD prior to the initial HF diagnosis, constituting the cardiorenal cohort. Mean age was 78.5 years; 50.8% were female. NT-proBNP testing before HF diagnosis was documented in 5.3% (n=237) of cardiorenal patients, with markedly elevated mean levels (2,315.7 pg/mL). Among HF+CKD patients not on SGLT2i prior to HF diagnosis (n=1,979; 931 male, 1,048 female), 24.1% (n=477; 26.5% male [247/931], 22.0% female [230/1,048]) received an initial SGLT2i prescription within 26 weeks after HF diagnosis. Mean time to initiation was 5.3 weeks (5.4 male, 5.2 female). Across the entire observation period, 1,946 cardiorenal patients received SGLT2i corresponding to 43.4% of the HF+CKD cohort (54.8% male [1,066/1,946], 45.2% female [880/1,946]). Conclusions In German primary care, patients with concomitant HF and CKD exhibit low rates of diagnostic confirmation using NT-proBNP and only moderate uptake of SGLT2i despite clear dual indications. Even when prescirbed, initiation is often delayed by several weeks. These findings highlight a persistent gap between guideline recommendations and practice. Strengthening diagnostic pathways, accelerating initiation and optimisation of GDMT - particularly SGLT2i - and improving cross-sectoral coordination should be prioritised. Equitable access, targeted clinician education, and appropriate reimbursement structures may help reduce morbidity, hospitalisations, and mortality in this high-risk population.