Percutaneous Nephrolithotomy: Short- and Long-Term Effects on Health-Related Quality of Life

Abstract

Background and Purpose:

Percutaneous nephrolithotomy (PCNL) is the treatment of choice for large and complex kidney stones, having increased its safety and effectiveness over the last years. Nonetheless, there is little known about its impact on quality of life (QoL). This study aimed at evaluating the effects of PCNL on patients' QoL in the short and long term.

Patients and Methods:

We prospectively studied 40 consecutive cases who underwent PCNL. QoL was measured using the short form-36 (SF-36) questionnaire, 2 weeks before surgery and then in the third postoperative month and a year after. Changes in QoL were assessed under statistical and clinical relevance criteria.

Results:

PCNL has rendered 70% of the cases completely stone free with a 35% complication rate (33% Clavien I+II). The baseline scores of all SF-36 domains were worse than the referral population. Three months after PCNL, bodily pain was the only dimension whose change was relevant for patients (effect size [ES]=0.71, minimal clinically important difference [MCID]=0.56). A year after, this favorable effect of PCNL on body pain is still present, being also beneficial on both role physical (ES=0.58, MCID=0.52) and the physical component summary (ES=0.56, MCID=0.43). Social function was also close to reaching clinical relevance a year after the procedure (ES=0.66, MCID=0.72).

Conclusion:

Kidney stone disease considerably affects the patients' QoL. PCNL not only has good outcomes rendering the kidney stone free without major complications but produces an immediate body pain relief. This is perceived as relevant by the patients even a year after the procedure, when some other physical aspects of QoL also get better, helping patients to restore their social activities.

Introduction

Urinary tract lithiasis affects 2%–3% of the population worldwide, with a 5% prevalence in Spain, and is considered a chronic disease sometimes associated with other morbidities.¹ It has been largely documented that urolithiasis considerably impacts health-related quality of life (HRQoL), mainly in those patients with recurrent stones or on whom several procedures have been done. Urinary stones usually limit patients' HRQoL, primarily causing pain and urinary tract infections.

Even though its deleterious effect on HRQoL is clear, few studies have been done to assess the impact of kidney stone treatments on patients' quality of life (QoL). These studies have been carried out using generic HRQoL questionnaires, the most used being the short form-36 (SF-36), because to date, there are no specific questionnaires validated for longitudinal studies in this regard. The Wisconsin StoneQoL is a promising specific survey whose test–retest reliability is close to being confirmed.² Until then, general HRQoL questionnaires are needed to assess the effects of kidney stone treatments on QoL.

Percutaneous nephrolithotomy (PCNL) is the treatment of choice for kidney stones larger than 2 cm or after other theoretically less invasive procedures fail.³ In the past, these cases where treated by open renal surgery, whose morbidity was relatively high, sometimes bringing about loss of kidney function. The PCNL technique has been improved in recent years, since the advent of new miniaturized endoscopes, stone fragmentation, and retrieval devices, thus lowering its invasiveness and rationally leading to a beneficial effect in patients' HRQoL.

The main goal of PCNL should be to render the kidney stone free, with minimum damage to the renal functional parenchyma, as well as improving the HRQoL of these patients in the short and long term. We studied a cohort of kidney stone patients treated by PCNL to determine the short- and long-term effects of this technique in HRQoL.

Patients and Methods

From June 2010 to June 2012, all the consecutive cases with kidney calculi and indication of treatment by PCNL were proposed to enroll in the study. Written informed consent was obtained for this investigation, which was carried out in accordance with the Principles of the Declaration of Helsinki and approved by the Ethics Committee of Clinical Investigation in Galicia, Spain. The study finally comprised 40 patients, with fewer than 5% of the candidates choosing not to participate in it.

PCNL was performed in all cases under general anesthesia, using the Galdakao-modified supine Valdivia position.⁴ To lessen the variability associated with different technical options, all the procedures were carried out by the same surgeons under the same protocol: X-ray and ultrasonographic puncture of the caliceal system, dilation with serial Amplatz dilators to a 24F caliber, and both a double-J ureteral stent and a 10F nephrostomy tube at the end of the surgery. The resources of endoscopic, lithotripsy, and stone retrieval devices did not vary during the study. The postoperative analgesic protocol was not different either. Nephrostomy tubes were taken out in the second postoperative day if no complications had appeared, and the double-J stent removal was scheduled in the second week after PCNL on an outpatient basis. Complications were classified using the modified Clavien-Dindo system.⁵ Success was defined as the complete absence of fragments in a CT scan performed in the third postoperative month.

The patients filled in themselves the validated Spanish version of the SF-36 questionnaire 2 weeks before surgery and then in the third postoperative month and a year after, during the course of a clinical visit. This SF-36 survey consists of 36 multiple-choice questions, which can be summarized into eight domains: physical function, role physical, bodily pain, general health, vitality, social function, role emotional, and mental health.^6,7 Each of these domains is scored from 0 to 100, with a higher score representing better health. By combining scores for each dimension, two summary aggregates are derived: the physical component summary (PCS) and the mental component summary. Scores of the eight domains and the two summary components were standardized to the Spanish general population, and normalized with a mean of 50 and a standard deviation of 10.⁸

Differences in HRQoL after PCNL were assessed under statistical (p<0.05) and clinical relevance criteria. For the latter, the effect size (ES), the standardized response mean (SRM), and the minimal clinically important difference (MCID) were estimated. The ES and SRM grade the magnitude of change, and both take values from 0 (no change) to 1 (complete change). The MCID is defined as the smallest difference in a score of a domain of interest that patients perceive to be beneficial and that would mandate, in the absence of troublesome side effects and excessive costs, a change in the patient's management.^9
–11 Changes whose ES and SRM were higher than their respective MCID were considered clinically relevant for the patients.

All analyses were carried out using SPSS 15.0 (SPSS, Inc., Chicago, IL). A value of p<0.05 was considered as statistically significant. The Kolmogorov–Smirnov test was performed to determine whether the data were normally distributed. Paired t-tests were used to test for significant differences between baseline SF-36 scores and those in the third month and a year after PCNL.

Results

Table 1 lists patient characteristics, as well as some technical aspects and the PCNL procedure outcomes. It is worth pointing out the uniformity in PCNL technical aspects, as well as the fact that we have operated on high stone burden cases, with a global complication (35%) and success rate (70%) similar to other series (Table 1).

Table 1.

Patient Characteristics, PCNL Technical Aspects, and Outcomes

No. patients	40
Age, years	55.7±11.7
BMI, kg/m²	29.3±4.7
No. male (%)	16 (40)
No. left kidney (%)	25 (62)
ASA score	1.7±0.7
Stone burden (mm²)	372 [273, 839]
Stone distribution
No. single (%)	11 (28)
No. multiple (%)	7 (17)
No. staghorn (%)	22 (55)
Operating time, min	95 [70, 143]
No. single percutaneous access (%)	40 (100)
No. Amplatz system dilation (%)	40 (100)
No. 24F caliber dilation (%)	40 (100)
Hospitalization, days	4 [3, 8]
Complications
No. Clavien I (%)	2 (5)
No. Clavien II (%)	11 (28)
No. Clavien IIIa (%)	1 (2)
No. success (%)	28 (70)

Results are expressed in mean±SD or median [p25, p75].

ASA=American Society of Anesthesiologists; BMI=body mass index; PCNL=percutaneous nephrolithotomy.

Table 2 shows baseline SF-36 scores as well as those in the third month and a year after PCNL in our series. All the baseline domains and summary components were considerably affected by the stone disease before surgery. Three months post-PCNL, many of them were close to the referral population mean. Physical function (p=0.013), role physical (p=0.004), bodily pain (p=0.000), mental health (p=0.031), and PCS (p=0.001) experienced statistically significant changes after PCNL. One year after, this overall improvement trend was confirmed, extending it to social function (p=0.004) (Table 2).

Table 2.

Baseline, Third Month, and 1-Year Post-PCNL SF-36 Scores

	Baseline (n=40)	Third month (n=40)	p-Value	Baseline (n=35)	1 year (n=35)	p-Value
Physical function	41.9±11.4	46.2±9.9	0.013^a	42.7±11.4	47.7±9.3	0.006^a
Role physical	38.1±13.2	45.4±11.4	0.004^a	40.1±13.5	45.7±12.6	0.012^a
Bodily pain	40.2±10.1	47.8±8.7	0.000^a	41.2±10.4	46.2±10.5	0.010^a
General health	44.4±9.4	45.2±9.2	0.447	45.1±10.0	45.0±7.6	0.940
Vitality	40.4±5.6	40.7±4.5	0.722	39.7±5.3	39.5±3.5	0.808
Social function	41.2±13.1	44.8±9.9	0.071	43.0±12.7	49.8±8.6	0.004^a
Role emotional	45.8±13.0	47.7±11.5	0.401	47.7±11.4	47.4±13.0	0.902
Mental health	46.7±11.7	50.4±11.2	0.031^a	49.0±10.9	49.9±8.4	0.559
PCS	38.7±11.3	44.4±9.8	0.001^a	39.3±11.7	45.0±10.7	0.001^a
MCS	47.1±11.9	47.9±10.4	0.712	48.9±10.6	48.2±9.8	0.669

p<0.05. Results are expressed in mean±SD. Third month and 1-year post-PCNL results are compared with the baseline SF-36 domains.

MCS=mental component summary; PCS=physical component summary; SF-36=short form-36.

Even though 5 out of 10 domains of the SF-36 were rendered statistically significant both in the third month and a year after PCNL, not all of these changes in HRQoL were perceived as clinically relevant by the patients.

Table 3 depicts the differences in HRQoL after PCNL, with the ES, SRM, and MCID of each SF-36 domain and summary component. In the third month, bodily pain was the only dimension whose change (ES=0.71; SRM=0.77) was bigger than its respective MCID (0.56 for ES; 0.61 for SRM). PCS was also close to reaching its clinical significance. Thus, in the short term, PCNL has a beneficial effect on the physical aspects of HRQoL, with body pain relief being the only one clinically perceived by the patients. A year after the procedure, this favorable effect of PCNL on bodily pain is still present, benefitting both role physical (ES=0.58, MCID [ES]=0.52 and SRM=0.63, MCID [SRM]=0.58) and PCS (ES=0.56, MCID [ES]=0.43 and SRM=0.72, MCID [SRM]=0.55). Finally, social function, whose change was close to reaching clinical relevance, considerably ameliorates a year after PCNL (Table 3).

Table 3.

SF-36 Domains Mean Score Changes in the Third Month and a Year After PCNL Treatment, with Their ES, SRM, and MCID

	Mean change	ES	SRM	MCID (ES)	MCID (SRM)
Physical function
Third month	4.3±10.4^a	0.38	0.41	0.56	0.61
1 year	5.0±9.8^a	0.51	0.59	0.53	0.62
Role physical
Third month	7.3±14.4^a	0.55	0.50	0.72	0.66
1 year	5.6±12.1^a	0.58	0.63	0.52	0.58
Bodily pain
Third month	7.2±9.2^a	0.71	0.77	0.56	0.61
1 year	4.9±10.4^a	0.59	0.58	0.57	0.55
General health
Third month	0.8±6.7	0.08	0.12	0.39	0.54
1 year	−0.1±7.2	0.06	0.08	0.45	0.59
Vitality
Third month	0.3±5.0	0.05	0.06	0.56	0.63
1 year	−0.2±4.8	0.16	0.19	0.64	0.75
Social function
Third month	3.6±12.2	0.27	0.29	0.62	0.67
1 year	6.8±12.7^a	0.66	0.68	0.72	0.74
Role emotional
Third month	1.9±16.2	0.15	0.12	0.88	0.71
1 year	−0.3±15.5	0.12	0.10	0.82	0.69
Mental health
Third month	3.7±10.4^a	0.31	0.35	0.54	0.60
1 year	0.9±9.2	0.27	0.35	0.53	0.67
PCS
Third month	5.7±10.0^a	0.50	0.57	0.54	0.61
1 year	5.7±8.8^a	0.56	0.72	0.43	0.55
MCS
Third month	0.8±13.0	0.07	0.06	0.71	0.66
1 year	−0.7±10.9	0.09	0.10	0.63	0.69

Third month and 1-year post-PCNL results are compared with the baseline SF-36 domains. Changes clinically relevant for patients in bold.

p<0.05. Results are expressed in mean±SD.

ES=effect size; MCID=minimal clinically important difference; SRM=standardized response mean.

Discussion

Stone disease affects patients' HRQoL both physically and mentally. Many other authors have previously demonstrated that this condition has a negative impact in several domains of the SF-36 survey.^12

–15 This deleterious effect probably comes from urolithiasis being a chronic condition, whose main symptom is pain, sometimes leading to depression and limiting social activities.^16,17 In our series, patients had worse scores in all the HRQoL domains than the Spanish referral population. Nonetheless, it must be taken into account that our study has only included large and complex kidney stones, thus probably overestimating the HRQoL impact of stone disease.

Bearing in mind this negative effect on HRQoL, the goal of urinary stone treatments should not only be stone clearance with the least complications but also the improvement in patients' HRQoL. Concerning classical outcomes, in 70% of cases, no residual stones in the third month CT scan were found. Our 35% complication rate is relatively high, but similar to many PCNL series, without observing high Clavien grades.¹⁸

The ideal way to assess HRQoL is to use specific questionnaires for the disease. Unfortunately, to date there is only one specific survey regarding urinary stones, whose test–retest reliability has not as yet been confirmed.² Meanwhile, when evaluating HRQoL changes after a specific stone treatment, we have to keep using generic questionnaires, SF-36 being the most commonly applied in this scenario. Despite their extended use, generic HRQoL surveys have some limitations, primarily the possible influence of other conditions directly related with the studied disease, as well as of changes in the socioeconomic level of the patients in the follow-up. Therefore, there is a strong need to design validated specific questionnaires for urolithiasis.

Our results show that PCNL produces an immediate body pain relief, which is the main problem these large stones cause in patients. This beneficial effect is even noticeable a year after the procedure, when some other physical aspects are also clinically ameliorated. Probably due to this physical HRQoL benefit, patients feel able to restore their social life. Although social function improvement 1 year after PCNL was important, it did not reach clinical relevance criteria, probably due to the small number of patients who completed the 1-year survey. Considering that stone disease primarily affects the physical components of HRQoL, it is not surprising that the main changes after PCNL are observed in these domains, with little impact in the psychological ones.

To date, this is the first prospective and longitudinal study carried out to address the effect of PCNL on QoL, taking patient baseline status into account. The rest of studies have a cross-sectional design, with only a postoperative survey.^19

–22 These studies showed that PCNL improves body pain, as well as some other physical and mental HRQoL domains.

Our study has some potential advantages. First, we have approximated to the importance of the changes in patients' HRQoL not only using statistical criteria but also looking for the clinical relevance of the PCNL effect. Second, the availability of the Spanish SF-36 questionnaire scores has allowed us to compare our results with the referral population.^23,24 Moreover, in our series, all the cases were performed by the same team, with similar experience in PCNL and under the same protocol, thus avoiding a surgeon-effect bias in our results. Finally, the inclusion bias risk is very low, due to the high percentage of responders to the survey, when compared with the 20%–30% of responders in the vast majority of studies.

Besides the use of generic questionnaires, our main drawback is the small number of patients included. This has hampered us in carrying out some interesting subanalysis with enough statistic power, as the possible differences in the effects of PCNL on HRQoL depend on the stone-free status or the presentation of complications. However, we have demonstrated that PCNL improves the patients' HRQoL in the short term, which is even more evident a year after the procedure. Nonetheless, future studies with more recruited cases and a longer follow-up are needed to confirm this beneficial effect on HRQoL. Another potential limitation of this study is our large incidence of female cases (60%) when compared with the Spanish control SF-36 data (52%). It has been previously described that gender has an impact in stone formers HRQoL.¹² Considering that women are those whose HRQoL is more affected by the stone disease, this slight difference could potentially skew the interpretation of our results.

We are convinced that, in a near future, endourologists will have to bear in mind several aspects in the decision-making process concerning urinary stones. Not only should they take into account the theoretical chances of rendering the patient stone free and the risk of developing complications but also the possible effects of the different therapeutic alternatives on QoL, looking for the best treatment option for their patients.

Conclusions

Stone disease considerably affects the patients' QoL. Despite treating large and complex stone cases, PCNL not only has good outcomes rendering the kidney stone free without important complications but produces an immediate body pain relief. This is perceived as relevant by patients, even a year after the procedure, when some other physical aspects of HRQoL also get better, helping patients to restore their social activities.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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