According to ANAES guidelines (2000) adapted from the international guidelines, kidney function should be regularly monitored in hypertensive patients in order to detect vascular nephropathy at an early stage and prevent kidney failure which is a major cardiovascular factor. The PHENOMEN survey was conducted between January and July 2001 on a representative sample of 16,358 patients suffering from hypertension being followed by a General Practitioner (GP). The population included patients from all 22 administrative regions in France.
Aims: To determine the prevalence of renal involvement in patients with hypertension (both treated and untreated); to compare the GP's subjective evaluation of the extent of renal involvement with a more objective assessment made according to ANAES guidelines.
Methods: Kidney function was evaluated by measuring plasma creatinine levels to derive a value for the creatinine clearance rate (CCR) using the Cockeroft-Gault formula.
Results: Out of the 16,358 patients included, plasma creatinine levels could be measured in 11,586 (76%) [53% men; 47% women, mean age = 63 +/- 12 years]: mean plasma creatinine = 90 +/- 49 mumol/l, i.e. a mean CCR of 83 +/- 32 ml/min. For 8,650 of the patients (75%), kidney function had been monitored in the preceding twelve months. The physicians defined their patient's kidney function as normal in 10,080 (87%) of cases whereas in reality, 4,411 of 8,650 (51%) were suffering from some degree of renal insufficiency (RI): in 2,422 (28%), RI was mild (> or = 60 CCR < 80 ml/min): in 1,903 (22%) RI was moderate (> or = 30 CCR < 60 ml/min). A minority of patients (44 i.e. 1%) showed severe RI (CCR < 30 ml/min).
Conclusion: Most GPs apply ANAES guidelines and order plasma creatinine assays. However, there is a discrepancy between how the physician "perceives" the seriousness of the renal insufficiency and a more objective measure based on the CCR figure. It would seem that the CCR derivative is insufficiently exploited despite the widespread availability of converters. Thus, the PHENOMEN survey has revealed that the extent of renal involvement in patients with hypertension still tends to be underestimated by GPs despite the major implications of this complication in terms of therapeutic strategy and global cardiovascular risk.