Review Finds Patients With CKD Are Less Physically Active Than Recommended

In a review published in Frontiers in Medicine, researchers found that patients with chronic kidney disease (CKD) had significantly lower physical activity than the recommended daily amount. According to past studies the authors cited, lack of physical activity could affect the prognosis and progression of CKD in older patients.

The goal of this review was to investigate the daily step count of patients with CKD at each stage of the disease and determine if it varied by stage. Daily steps were used as an indicator of moderate physical activity, a recommended treatment to slow the progress of CKD.

For this review, the researchers used PubMed, Embase, and the Web of Science to look for relevant studies from inception to November 3, 2021. The researchers also manually retrieved other reviews on the subject in order to look for other studies.

Studies were identified as relevant if they included participants with CKD regardless of age or disease stage, used a device that measured daily step count, were observational studies, and had specific numbers of patient steps in their data. Studies were excluded if they included patients with acute kidney failure, were not written in English, or were clinical intervention trials, commentaries, reviews, conference abstracts, case reports, protocols, or editorials. Two of the authors looked through all potential studies to identify these inclusion and exclusion criteria.

Two of the authors extracted the authors, publication year, sample size, participants’ age, daily step counts, and assessment tools from the studies chosen. For quantitative analysis, the mean (SD) results and sample size were extracted. If a study reported findings from 2 different stages of CKD, both sets of data were included in the meta-analysis. Quantitative data synthesis was used to present the data in the studies. Heterogeneity between studies was calculated using the χ² test of Cochrane’s Q statistic, and I² estimates greater than 75% were considered highly heterogeneous.

There were 464 articles found in the initial search, with 198 articles subsequently excluded due to duplication. Another 196 articles were filtered out due to irrelevance. Eight more articles of the remaining 36 were removed based on exclusion criteria. The remaining 28 articles were used for this review.

Of the 3769 participants in 28 studies used, patients receiving hemodialysis were the most commonly reported population. The age range of the participants was between 15.1 and 70.9 years. Of the 28 studies, 22 were cross-sectional, 2 used a longitudinal design, and 4 were cohort studies. The overall step count of the included participants was 4642.47 (95% CI, 4274.18-5010.76) for patients with CKD.

Subgroup analysis was also performed to evaluate the daily step count for patients with different stages of CKD. Step counts for predialysis patients (5638.37; 95% CI, 4052.48-7224.25) were reported in 2 studies, step counts for peritoneal dialysis patients (4264.08; 95% CI, 3546.29-4981.87) were reported in 3 studies, and step counts for hemodialysis patients (4111.82; 95% CI, 3760.87-4462.77) were reported in 22 studies. There were 4 studies that gave step counts for patients who had received a kidney transplant (8689.83; 95% CI, 6702.46-10,677.20).

The researchers also found that daily step counts varied by whether patients had undergone dialysis on that day. A pooled analysis showed that, on a dialysis day, patients walked 3413.24 steps (95% CI, 2825.61-4000.88), with high heterogeneity (I² = 93.1%), whereas the overall step count on a nondialysis day was 4197.83 (95% CI, 3631.92-4763.75), also with high heterogeneity (I² = 89.0%).

Only 4 studies showed step counts of patients with CKD compared with healthy individuals. A random-effects model was used to identify that patients with CKD had a much lower step count than healthy individuals by a statistically significant margin (mean difference: −4034.10; 95% CI, −5662.73 to −2405.46).

The researchers also found that daily step counts were higher among people living in the Americas and among people who had previously had a kidney transplant. Participants younger than 60 years were also found to have more daily steps than those 60 years and older. Age, location, and stage of CKD were all included in the multivariable regression analysis. The results of that analysis were statistically significant (R² = 51.12%; P < .001) and reduced the I² from 93.5% to 89.5%. However, there were no other variables that remained statistically significant.

There were some limitations to this study. The statistical heterogeneity was high and remained in the subgroup analysis, which the authors wrote is difficult to avoid in a meta-analysis of observational studies. Large portions of the heterogeneity in the studies cannot be explained, however. The lack of non-English studies may have contributed to publication bias. The current review focused on literatures retrieved in standard databases, which means gray literature and unpublished articles were not included, although CKD studies on daily step counts may have been included in either form of literature.

The authors wrote that the data in this study identified patients with CKD as walking less than the 7000 to 10,000 steps per day recommended by the World Health Organization. The review revealed that the number of steps per day directly correlated with severity of CKD, with patients receiving hemodialysis walking significantly less than patients with CKD in the predialysis stage of the chronic disease. Participants who had had a kidney transplant in the past also reported significantly more daily steps, which further demonstrates the correlation between healthier patients and physical activity.

They further elaborated on their finding that older adults reported fewer daily steps, as older adults are more likely to experience the comorbidities of frailty and inflammation. Physical activity can help stem some of the issues associated with these comorbidities, so the importance of walking should be emphasized in this age group, according to the review authors.

The researchers wrote that additional evidence on long-term changes in physical activity for patients with CKD is required to draw further conclusions on the effects of improved physical activity. They also said that future studies should focus on early intervention to evaluate the effects of early changes in physical activity on CKD progression.

Reference

Zhang F, Ren Y, Wang H, Bai Y, Huang L. Daily step counts in patients with chronic kidney disease: a systematic review and meta-analysis of observational studies. Front Med. 2022;9:842423. doi:10.3389/fmed.2022.842423