Hidden chronic renal insufficiency and cardiovascular events in patients with hypertension in a primary care center

Research inefficiencies in external validation studies of the Framingham Wilson coronary heart disease risk rule: A systematic review

BACKGROUND

External validation studies create evidence about a clinical prediction rule's (CPR's) generalizability by evaluating and updating the CPR in populations different from those used in the derivation, and also by contributing to estimating its overall performance when meta-analysed in a systematic review. While most cardiovascular CPRs do not have any external validation, some CPRs have been externally validated repeatedly. Hence, we examined whether external validation studies of the Framingham Wilson coronary heart disease (CHD) risk rule contributed to generating evidence to their full potential.

METHODS

A forward citation search of the Framingham Wilson CHD risk rule's derivation study was conducted to identify studies that evaluated the Framingham Wilson CHD risk rule in different populations. For external validation studies of the Framingham Wilson CHD risk rule, we examined whether authors updated the Framingham Wilson CHD risk rule when it performed poorly. We also assessed the contribution of external validation studies to understanding the Predicted/Observed (P/O) event ratio and c statistic of the Framingham Wilson CHD risk rule.

RESULTS

We identified 98 studies that evaluated the Framingham Wilson CHD risk rule; 40 of which were external validation studies. Of these 40 studies, 27 (67.5%) concluded the Framingham Wilson CHD risk rule performed poorly but did not update it. Of 23 external validation studies conducted with data that could be included in meta-analyses, 13 (56.5%) could not fully contribute to the meta-analyses of P/O ratio and/or c statistic because these performance measures were neither reported nor could be calculated from provided data.

DISCUSSION

Most external validation studies failed to generate evidence about the Framingham Wilson CHD risk rule's generalizability to their full potential. Researchers might increase the value of external validation studies by presenting all relevant performance measures and by updating the CPR when it performs poorly.

Non-proteinuric diabetic nephropathy is the main cause of chronic kidney disease: Results of a general population survey in Spain

BACKGROUND

Diabetic nephropathy traditionally produces significant proteinuria prior to the development of renal impairment. However, this clinical paradigm has recently been questioned. The current study evaluated the impact of diabetes mellitus on the prevalence of renal disease in general population.

METHODOLOGY

Data from of the HERMEX survey, an observational, cross sectional, population based study were used. The final sample included 2813 subjects (mean age 51.2 years, 53.5% female). Four hundred patients have diabetes. Urinary albumin excretion (UAE) rate was analyzed and glomerular filtration rate (GFR) was estimated using the CKD-EPI formula.

RESULTS

Among participants without diabetes, 2.9%(2.2-3.6) had a GFR < 60 ml/min. Prevalence of abnormal UAE in population without diabetes was 3.3% (2.6-4.0). The global prevalence of renal disease was 5.6%(4.8-6.6). Prevalence of GFR <60 ml/min in subjects with diabetes was 8.8%(6.4-11.9)(p<0.001,Chi-square test). Prevalence of abnormal UAE in population with diabetes was 14.1%(7.7-19.8)(p< 0.001,Chi-square test). CKD prevalence was 20.3%(16.6-24.6)(p<0.001,Chi-square test). The logistic regression analysis showed a positive independent association of CKD with age, high blood pressure and albuminuria. No significant relationship was found with diabetes mellitus CONCLUSIONS: CKD is more prevalent in population with diabetes. Nevertheless, most of patients with diabetes and CKD have no albuminuria. An increased cardiovascular burden seems to produce this clinical presentation.

Prevalence of secondary hyperparathyroidism in patients with stage 3 and 4 chronic kidney disease seen in internal medicine

OBJECTIVE

Despite the high prevalence of chronic kidney disease in the elderly population, few data are available on the frequency of secondary hyperparathyroidism in the Spanish population affected by this problem. We undertook a study on this issue in patients attending the internal medicine departments in our area.

DESIGN AND METHODS

An observational, cross-sectional survey performed at internal medicine departments on 415 patients with stage 3 and 4 chronic kidney disease. Clinical history and risk factors were collected using a standardized protocol. Serum creatinine, phosphate, calcium, intact parathormone (PTH) and 25-hydroxy-cholecalciferol (25-OH-vitD) levels were measured in all patients.

RESULTS

Among stage 3 patients, 62.9% had PTH levels ≥70pg/mL and 32.7% levels ≥110pg/mL. Median PTH level in stage 4 patients was 120pg/mL (p <0.001), and 77.9% of these patients had PTH ≥70pg/mL (p <0.001) and 54.1% ≥110pg/mL (p=0.015). Adequate 25-hydroxy-cholecalciferol levels were found in only 7.2% of stage 3 patients and 4.1% of stage 4 patients. Only 7.2% of stage 3 patients had hyperphosphatemia, as compared to 25.4% of stage 4 patients (p <0.001).

CONCLUSIONS

Hyperparathyroidism is a common complication of stage 3 and 4 chronic kidney disease which is not associated to detectable changes in serum calcium and phosphate levels. It is therefore advisable to measure PTH levels in all patients with decreased glomerular filtration rate.