Clinical pharmacy services are crucial for CKD patients who require a complicated course of treatment [7]. With the use of this service, medical professionals such as physicians, nurses, dietitians, and clinical pharmacists work together as a multidisciplinary team to better manage CKD-related comorbid disorders [7]. In this study, we found that DRPs were present in 48.7% of the CKD patients. Although most (91.7%) DRP interventions were accepted by the physicians, and patient, 71.7% of DRPs were fully resolved. Treatment efficacy was found to be the main type of DRPs (56.2%).

In our study, 269 CKD patients were followed up. During the period, a total of 205 DRPs were found in 131 (48.7%) of 269 individuals. In a recently published meta-analysis research analyzing DRPs in hospitalized CKD patients, the prevalence of DRP was reported to range between 12 and 87% [8]. In studies conducted to investigate DRP, including CKD patients undergoing dialysis, Liu et al. [19] found DRP in 77% of patients, and Holm et al. [20] in 62% of patients. The fact that hemodialysis patients were excluded from our study may explain the higher prevalence of DRP in the two studies in comparison to our finding. In a French investigation of 103 patients with chronic renal disease, 394 DRPs were found in 93.2% of the patients. The comorbidity that arises with aging and the rising number of medications were associated with high risk of DRP in this study [21].

The average number of DRPs per patient was found to be 0.76 in the present study. This number varies between 0.36 and 3.8 in studies conducted in different countries [21,22,23,24,25]. Although each trial was conducted on CKD patients, the explanation for the disparate outcomes can be attributed to the fact that the number of medicines utilized varied depending on the patient subgroups covered.

In our study, the number of medicines was significantly higher in patients with DRP than without DRP (9.6 ± 3.6 and 8.1 ± 3.5, respectively) during their hospital stay (p < 0.05). Similarly, in a study conducted with 5217 chronic kidney patients in Germany, it was shown that each patient used an average of 8 drugs while in hospital [26].

This study found that 268 patients (99.6%) had at least one comorbidity. There were three or more comorbidities diagnosed in 72.1% of individuals. The most common comorbidities were found to be HT (67.3%), DM (39.4%), and atherosclerotic heart disease (22.3%). Similarly, HT, DM and anaemia are among the most common comorbidities in the study of Subeesh et al., and HT, DM, and CAD in the study of Rani et al. [22, 23]. However, there was no statistically significant difference in our study between individuals with (2.7 ± 1.4) and without (2.5 ± 1.6) DRP in terms of the presence of comorbidities (p > 0.05).

Clinical pharmacy services in hospital settings are beneficial in lowering treatment costs and delivering better treatment outcomes through the identification and resolution of DRP, according to substantial evidence in the literature [27,28,29,30]. Supporting these results, the length of hospital stays of patients with DRP (11.3 ± 7.7%) was found longer than patients without DRP (9.3 ± 7.7%) (p < 0.05). This finding implies that drug-related problems could have a negative impact on the efficacy and safety of the treatment as well as be a factor that raises the cost of care by extending the patient’s stay in the hospital.

In the current study most DRPs were related to either treatment effectiveness (50.7%) or treatment safety (43.9%). Likewise, Liu et al. [19] and Dvorackova et al. [24] found that the most frequent problems were treatment efficacy and drug selection as the cause in their analysis of PCNE in CKD patients. Drug interactions (21.8%) were identified by Njeri et al. [31] as the most frequent cause of DRPs. Drug interactions were found about 14% of the causes of DRPs in our study. Differently Subeesh et al. [22] found that drug interactions were the most common cause of DRP in CKD patients, including dialysis patients, at a high incidence (60%) according to PCNE assessment. Since dialysis patients taking more medications than other CKD patients, there may be a greater cause of drug interactions.

Gastrointestinal medications (18.0%), lipid metabolism drugs (13.6%), and antimicrobial drugs (11.7%) ranked 1–3 in the study’s analysis of the drug groups that are associated with DRPs. Compared to literature it is seen that antibiotics and medications for the gastrointestinal system are the two drug classes that most often associated with DRPs in individuals with chronic kidney disease [21, 24, 25].

In our study, over 92% of the suggestions given in relation to the issues found for DRP were accepted by physicians. This rate resembles results found in previous studies published in the CKD literature [19, 20, 32].

Despite the study’s high acceptance rate (91.7%), the rates of fully resolved DRP, partially resolved DRP, and unresolved DRP were 71.7%, 1.9%, and 23.4%, respectively. In a study conducted by Liu et al. [19], 76.1% of interventions were accepted, and 68.3% of DRPs were completely resolved. In a different study by Garedow et al. [25], 81.6% of interventions were accepted, and 79.8% of DRPs were fully resolved. Surprisingly, the percentage of resolved DRP in the study of Adibe et al. was very low. (7.9%) [33]. Although the rates of resolved DRPs were comparable, the cause of DRPs remained unresolved in our study may be related to logistics factors. The high acceptance rate of interventions and relatively high rates of resolved DRPs indicate the willingness of other healthcare providers to collaborate with clinical pharmacists. This is also an opportunity for optimizing care and practice of clinical pharmacy in Turkey.

This study has the following limitations. The lack of control group may attenuate the discrimination of the impact of clinical pharmacist from other factors that may lead to resolving DRP. We did not include dialysis patients as it is well studied in literature and our interest was in patients before they reach this stage to explore missed opportunities of care before reaching dialysis stage. Evaluation of long-term effect and impact on primary outcomes such as progression to an advanced stage of CKD and the need to be on dialysis was not done due to the limitations in logistics and financial support. Due to these reasons as well, the research was carried in one center. The results cannot be generalized to all CKD patients regarding DRPs because the study was only done in one center. We recommend further controlled multicenter studies, characterize to prevalence of DRP in CKD patients and the impact clinical pharmacist’s interventions. Another limitation is, although many factors related to the patient were evaluated, the effect of patient’s health literacy could not be evaluated in this study. Health literacy and patient’s compliance in patients can increase the number of problems related to drugs. Therefore, further studies are needed to examine these factors.

There are also strengths with the method used in this study. DRPs were evaluated in multidisciplinary healthcare teams, which may have resulted in a higher rate of interventions to the DRPs due to face-to-face conversations and interventions. Additionally, this is the first study that reports DRPs in nephrology ward by clinical pharmacists in Turkey.