title: Oversight: a retrospective study of biochemical monitoring in patients beginning antihypertensive drug treatment in primary care.
abstract: BACKGROUND
  Guidelines recommend biochemical monitoring of patients treated with antihypertensive agents, although there is little primary evidence for these recommendations.
  
  
  CONCLUSIONS
  Patients treated for hypertension in general practice often have no biochemical tests before, or in the 6 months after, starting drug treatment.
  
  
  OBJECTIVE
  Guidelines on the management of hypertension have recommended baseline testing of serum electrolyte and creatinine concentrations before treatment since the 1990s. We wished to examine the extent of laboratory monitoring in patients with newly diagnosed hypertension and newly treated with antihypertensive drugs.
  
  
  METHODS
  We carried out a retrospective analysis of 74,096 patients in the General Practice Research Database (GPRD) aged 18 years and older with newly diagnosed hypertension and prescribed a single antihypertensive agent. We determined the number of patients with a laboratory test for serum electrolyte and creatinine (or urea) concentrations prior to the first antihypertensive drug prescription and in the 6 months after and patient factors associated with subsequent monitoring.
  
  
  RESULTS
  Thirty-four thousand nine hundred and forty-seven patients (47%) had at least one biochemical test in the 12 months prior to beginning antihypertensive treatment, and 26,946 (36%) had at least one biochemical monitoring test in the 6 months after beginning antihypertensive treatment. Thirteen thousand five hundred and four (18%) had both baseline and monitoring tests. Baseline tests were normal in 11,671 patients (86%), of whom 10,213 (88%) had normal tests at first monitoring. Monitoring was significantly more likely in patients treated with ACE inhibitors than thiazides (adjusted OR 1.90; 95% CI 1.80, 2.00), older patients (adjusted OR 1.23; 95% CI 1.11, 1.36) [individuals aged 80-89 years compared with <40 years], and patients with diabetes mellitus (adjusted OR 2.03; 95% CI 1.91, 2.16).
  
  
  CONCLUSIONS
  Biochemical testing at baseline and monitoring after starting treatment is often omitted in newly diagnosed hypertensive patients. When both are tested, one in eight normal results becomes abnormal.
authors.affiliation: Department of Clinical Pharmacology, University of Birmingham, Birmingham, UK.
authors.forename: Jamie J
authors.initials: JJ
authors.lastname: Coleman
authors.forename: Sarah E
authors.initials: SE
authors.lastname: McDowell
authors.forename: Stephen J W
authors.initials: SJ
authors.lastname: Evans
authors.forename: Paramjit S
authors.initials: PS
authors.lastname: Gill
authors.forename: Robin E
authors.initials: RE
authors.lastname: Ferner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000009:adverse effects* / Q000627:therapeutic use; D016903:Drug Monitoring; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D005791:Patient Care / Q000379:methods / Q000592:standards*; D011320:Primary Health Care / Q000379:methods* / Q000592:standards; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D000959:Antihypertensive Agents