Changes in Systolic Blood Pressure over Time in Cats with Chronic Kidney Disease

Bijsmans E.S., Jepson R.E., Chang Y.M., et al.

American College of Veterinary Internal Medicine, 2013. p.732-733.


The association between hypertension and feline chronic kid- ney disease (CKD) is well recognised and the prevalence of hypertension in CKD has been reported to be between 19.4% and 65%. The objectives of this study were to assess the preva- lence of hypertension in cats with CKD seen in a first opinion clinical setting and to investigate subsequent changes in systolic blood pressure (SBP) over time in cats that were initially normo- tensive.Cats with CKD ! 9 years old that were examined for the first time at two first opinion practices in London, UK between August 2000 and August 2012 and with a follow up period of 3 months and a minimum of 3 visits were retrospectively identified. CKD was diagnosed in cats with renal azotemia (plasma creatinine concentration >2.0 mg/dl either on two con- secutive visits or in conjunction with USG <1.035). SBP was measured at all visits by a non-invasive Doppler technique. Cats with SBP ! 170 mmHg on two consecutive visits or SBP ! 160 mmHg with concurrent evidence of hypertensive retinopa- thy/choroidopathy were classified as hypertensive. Exclusion criteria were concurrent hyperthyroidism or treatment with med- ications known to alter SBP. Re-examination of cats was offered at a maximum of 8 week intervals. The slope of SBP over time curves were compared between cats that developed hypertension during follow-up (DH-group) and those that remained normo- tensive throughout (NT-group) using a mixed effects model. SBP at diagnosis of CKD was compared in the two groups using a Welch two sample t-test. In the DH-group the actual SBP measurements that resulted in the diagnosis of hypertension were not included in the analysis. In the NT-group all available data were included. Results are expressed as mean ` standard deviation.

Two hundred and sixty eight cats met the inclusion criteria. Of these, 102 cats (38.1%) were hypertensive at diagnosis of CKD or were diagnosed as hypertensive within 3 months of CKD diagnosis and 33 cats (12.3%) became hypertensive ! 3 months after diagnosis of CKD (DH-group). The remainder (133 cats; 49.6%) remained normotensive throughout follow-up (NT- group). At diagnosis of CKD, mean SBP was significantly higher in the DH-group than in the NT-group [154.2 ` 14.1 vs. 135.0 ` 17.0 (P < 0.0001)]. Cats in the DH-group were diag- nosed as hypertensive a median of 385 [range 91-1918] days after diagnosis of CKD. Cats in the NT-group had a median of 329 [range 91-2037] days of follow up. The slope of SBP over time was significantly greater in the DH-group than the NT-group [1.7 ` 1.8 mmHg per 100 days vs. 0.5 ` 1.6 mmHg per 100 days (P < 0.001)]. About 12% of cats that are normotensive at the time of CKD diagnosis will develop hypertension over time. Interestingly these cats have higher baseline, and a greater rate of increase, of SBP over time than their nomotensive counterparts. The high preva- lence of hypertension in azotemic cats in this study shows the importance of monitoring of SBP.