Socio-economic status influences chronic kidney disease prevalence in primary care: a community-based cross-sectional analysis

Nephrol Dial Transplant. 2015 Jun;30(6):1010-7. doi: 10.1093/ndt/gfu408. Epub 2015 Jan 13.


Background: Primary care chronic kidney disease (CKD) registers report widely varying prevalence within the UK. We examined the effects of laboratory ascertainment and adjusting for practice-level variables on the variation in CKD prevalence. We carried out an Ayrshire-wide laboratory database analysis of primary care practices (PCPs).

Methods: We analysed 54 PCPs with 313 639 registered patients aged ≥ 18. All patients with a low estimated glomerular filtration rate (<60 mL/min/1.73 m(2)) had their serum creatinine values extracted from 1st January 2009 to 31st March 2012. Individuals with CKD stage 3-5 were identified with an algorithm that confirmed chronicity. These data were linked to PCP attributes from Information Services Division, Scotland. Using laboratory-ascertained CKD prevalence, we examined whether adjusting for practice-level factors [socio-economic status (SES), rurality and patients to general practitioner ratio (PGR)] and patient-level factors (age, gender) explained some of the observed variation among PCPs. Individual and combined hierarchical multilinear regression models were used.

Results: Eighteen thousand two hundred and eighty-five (5.8%) had CKD stage 3-5 on 31 March 2011. SES, rurality and PGR predicted 39% (F(3,50) = 12.37, P < 0.001) of the variation in prevalence with SES exerting the most influence (25%). With the stepwise addition of explanatory variables, variation between practices fell from 3.9-fold using PCP register prevalence to laboratory ascertained (3.1-fold variation), with age and gender adjustment (further fall to 2.1-fold), and lastly to 1.8-fold variation with adjustment for SES. Funnel plots using these adjustments reduced the number of outliers outside of 3 SD from 15 to 7 to 6, and outliers between 2 and 3 SD by 16 to 13 to 5.

Conclusions: Laboratory ascertainment is practicable, reduces variation and facilitates benchmarking. PCP attributes other than age and gender impact on prevalence. Over a third of variation in CKD prevalence among PCPs can be explained by rurality, PGR and especially SES even after age and gender stratification.

Keywords: Scottish index of multiple deprivation; chronic kidney disease; laboratory ascertainment; rurality; variation.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Community-Based Participatory Research*
  • Cross-Sectional Studies
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Kidney Function Tests
  • Male
  • Middle Aged
  • Practice Patterns, Physicians'*
  • Prevalence
  • Primary Health Care*
  • Renal Insufficiency, Chronic / diagnosis
  • Renal Insufficiency, Chronic / epidemiology*
  • Risk Assessment
  • Scotland / epidemiology
  • Social Class*
  • Young Adult