Health Related Quality of Life DiffersBetween Male and Female Stone FormersKristina L. Penniston and Stephen Y. Nakada*,†From the Department of Surgery, Division of Urology (KLP, SYN) and the Department of Medicine, Nephrology Section (SYN), Universityof Wisconsin School of Medicine and Public Health, Madison, Wisconsin

Purpose: Chronic urolithiasis often results in long-term health complications, frequent clinic visits, multiple interventionsand disruptions to patients’ lives. While the most valued treatment end point has been stone-free status, patient healthrelated quality of life should also be considered. Little is known about health related quality of life in stone formers. Wecharacterized the health related quality of life of stone formers at our institution.Materials and Methods: After institutional review board approval all adult stone formers treated at our Metabolic StoneClinic from 1995 to 2006 were invited to participate. Of these patients 189 (36%) completed the SF-36v2™ Health Survey, avalidated, 36-item, generic health and well-being questionnaire addressing physical, social and emotional domains. Com-parisons of scores were made with those of U.S. norms and within-sample for demographic and clinical variables. Statisticalanalyses included independent sample t tests and ANOVA.Results: Compared to healthy adults, stone formers reported lower health related quality of life for general health (64.9 �1.6) and bodily pain (69.4 � 1.6), and women reported greater impairment (61.4 � 2.4 and 66.5 � 2.4, respectively).Comorbidities such as depression, diabetes, hypertension and overweight/obesity contributed to lower scores for many healthdomains.Conclusions: The health related quality of life of stone formers, especially women, is compromised compared to U.S. norms.Women stone formers scored lower than men for physical and mental health. Clinicians should be aware of the risk ofimpaired health related quality of life in stone formers. A new and promising end point in the management of urolithiasis isimprovement of health related quality of life. Studies that identify treatment strategies that maintain or improve healthrelated quality of life for individual patients are warranted.

Key Words: quality of life, kidney calculi, urolithiasis

Urolithiasis is a debilitating condition with a reportedincidence of 10% to 15% among residents of theUnited States.1 The total annual direct cost of uro-

lithiasis in the U.S. is estimated to be nearly $2.1 billion.2

Urinary stones typically affect people during their mostactive and productive stage between 20 and 50 years old.1

Urolithiasis is a chronic disease, often with a protractedclinical course. Decreased productivity, loss of work time oremployment, renal failure and death, although extremelyrare, are documented outcomes of recurrent urolithiasis.3

The lifetime recurrence rate for urinary stone formers is50%, with the interval between recurrences estimated to be10% within 1 year, 35% to 50% in 5 years and 50% or moreby 10 years.2

The primary end point for treatment of urolithiasis hashistorically been a stone-free state. Indeed, stone removalhas been improved with the advent of minimally invasivetechniques, but there is increasing interest in health effects,

Submitted for publication March 20, 2007.Study received institutional review board approval.* Correspondence: Department of Urology, University of Wiscon-

sin School of Medicine and Public Health, 600 Highland Ave.,G5/339 Clinical Science Center, Madison, Wisconsin 53792-3236(telephone: 608-263-1359; FAX: 608-262-6453; e-mail: nakada@surgery.wisc.edu).

† Financial interest and/or other relationship with Cook Urologi-cal, Inc.

0022-5347/07/1786-2435/0THE JOURNAL OF UROLOGY®

Copyright © 2007 by AMERICAN UROLOGICAL ASSOCIATION

2435

potentially adverse, of even the least invasive options.4 Anoutcome that may be especially relevant to patients is qual-ity of life. Surprisingly, little is known about the healthrelated QOL of patients with recurrent urolithiasis, many ofwhom undergo multiple procedures during the course oftheir disease, report for numerous clinic appointments andtake 1 or more medications to control the metabolic aspectsof the disease. Patients with more active stone disease fre-quently report missing work and family events due to com-plications of urolithiasis. Yet it is not known whether activestone disease predicts decrements in QOL. Pain is a fre-quently reported effect of recurrent urolithiasis, yet it can behighly variable among individuals, even among those withsimilar stone profiles. With no direct one-to-one relationshipbetween disease severity and symptoms, health related QOLcould help clinicians appreciate the individual and variableeffects of similar disease status and treatment modalities,and use this information in establishing appropriate goalsfor disease management.

To our knowledge no study has previously been publishedthat assessed the general health related QOL of stone form-ers at various disease stages. Studies on the health relatedQOL of stone formers are limited to those involving patientpreferences in the treatment of urinary stones,5 stent place-ment6–8 and QOL following extracorporeal SWL or other

surgical modalities.9,10 The objective of this cross-sectional

Vol. 178, 2435-2440, December 2007Printed in U.S.A.

DOI:10.1016/j.juro.2007.08.009

HEALTH RELATED QUALITY OF LIFE OF PATIENTS WITH KIDNEY STONES2436

study was to characterize the relationships between demo-graphic and clinical variables and the health related QOL ofpatients with urolithiasis from our metabolic stone center.

METHODS

SubjectsParticipants were recruited from the database of patientstreated at the Metabolic Stone Clinic of the University ofWisconsin Hospital and Clinics (Madison, Wisconsin), acomprehensive program including a multidisciplinary teamof nephrologists, urologists and a Registered Dietitian. Typ-ically patients with a putative metabolic basis for urolithia-sis are referred to the MSC by urologists. Since its inceptionin 1995 the MSC has treated nearly 600 patients, the ma-jority of whom have calcium stones. Of the patients withviable addresses and contact information, 520 received aninvitation to participate in this cross-sectional survey study.We did not select for patients with a particular stoneprofile or for any other criteria other than having been orcurrently being a patient of the MSC. A total of 189subjects completed and returned the questionnaireswithin the requested time frame resulting in a responserate of 36.4%. A statistical comparison of the age of re-sponders (189) and nonresponders (331) demonstratedboth groups to be comparable (p �0.05, table 1). Womenslightly overresponded compared to their percentage ofthe total patient population. While women represent 44%of the patient population within the MSC, the surveyrespondents were 47% women. However, the gender com-position of responders vs nonresponders was not statisti-cally significant (p �0.05, table 1).

ProceduresWe used a cross-sectional design to assess the health relatedQOL of patients with urolithiasis. The University of Wiscon-sin-Madison Health Sciences institutional review board ap-proved all procedures in compliance with the Health Insur-ance Portability and Accountability Act. Data collectionincluded a self-administered questionnaire which wassent in the mail to each subject who provided consent, as

TABLE 1. Age and gender characte

Responders

No. pts (%) 189 (36.3)Mean pt age at first clinic visit � SEM 50.9 � 0.94No. male (%) 100 (53)No. female (%) 89 (47)Mean male age � SEM 52.3 � 1.2Mean female age � SEM 49.3 � 1.4No. male age (%):

18–24 1 (33)25–34 8 (28)35–44 18 (30)45–54 30 (36)55–64 25 (33)65 or Older 18 (42)

No. female age (%):18–24 4 (25)25–34 10 (30)35–44 21 (38)45–54 22 (46)55–64 21 (43)65 or Older 11 (44)

* p Values comparing age of responders to nonresponders are from 2 sample t

of male responders vs nonresponders is from Fisher’s exact test.

well as followup telephone calls to remind subjects toreturn the questionnaire and/or to obtain missing infor-mation, and medical record abstraction. Subjects who pro-vided consent received up to 3 followup telephone calls asreminders to return the questionnaires. The survey in-strument was the SF-36v2™ Health Survey, a validated,36-item, generic health and well-being questionnaire ad-dressing 8 QOL domains and including 1 general healthrating item, which asks respondents about the amount ofchange in their general health during a 1-year period.Subjects who returned the questionnaires were given a$10 gift certificate to a restaurant with multiple locationsin the region.

Demographic information, stone composition, date(s) andvisit(s) to the MSC, history of surgical procedures and emer-gency room visits, comorbidities, and other medical historydata were collected (table 2) using a data collection form andextraction of data from medical records. A statistical com-parison of these demographic variables between men andwomen responders was made (table 2). Information aboutstone composition was obtained from the medical recordsand included reports of actual stone analyses as well asreports by the nephrologist and/or urologist who evalu-ated the patients. Participants with evaluable informa-tion were overwhelmingly calcium stone formers (94%).Those known or presumed to have any type of calciumstone, including those in combination with other stonetypes, accounted for 93% and 97% of the women and men,respectively. Within our sample 5 women and 1 man hadcystine stones, and 2 women and 7 men had pure uric acidstones.

Statistical AnalysisScores for the 8 domains of the SF-36 were transformed to a100-point scale and higher scores indicated better healthrelated QOL. We compared QOL scores within our sampleusing 2-sample t tests under the assumption of equal vari-ances. When a test for equal variances showed that theywere unequal, we used a Satterthwaite correction. In situa-tions in which more than 2 groups were being compared we

s of responders vs nonresponders

Nonresponders All Invited p Value*

331 (63.7) 520 (100)48.9 � 0.75 49.6 � 0.59 0.092193 (58) 293 (56) 0.23138 (42) 227 (44)

51.1 � 0.92 51.5 � 0.73 0.4345.7 � 1.2 47.2 � 0.94 0.060

2 (67) 320 (71) 2841 (69) 5954 (64) 8451 (67) 7658 (13) 43

12 (75) 1623 (70) 3335 (62) 5626 (54) 4828 (57) 4956 (10) 25

under the assumption of equal variances. p Value comparing the percentage

ristic

tests

pain/s

HEALTH RELATED QUALITY OF LIFE OF PATIENTS WITH KIDNEY STONES 2437

used an ANOVA and performed pairwise comparisons withFisher’s protected least significant difference tests. To de-termine which comorbidities had the largest impact onhealth related QOL scores we used a multiple regressionapproach. We also applied the multiple regression approachwith respect to gender after differences for some domains be-tween men and women were detected. p values �0.05 wereconsidered significant. All analyses were performed usingSAS® statistical software version 9. To determine themagnitude of the differences between our sample popula-tion and those of published U.S. norms (derived from aracially diverse, nationwide, cross-sectional study of 2,474persons without chronic disease 18 years old or older), adifference of 5 or more points from the norms was consid-ered clinically relevant for all health related QOL do-mains except for role-physical and role-emotional, forwhich a 10-point difference was required for a sample ofthis size.11

RESULTS

Comparison to U.S. NormsCompared to healthy U.S. adults patients with urolithiasisreported lower health related QOL for general health andbodily pain (64.9 � 1.6 and 69.4 � 1.6, respectively) but notfor other domains (table 3). Compared to respective gendernorms from the U.S. population sample, women with uro-lithiasis reported greater impairment than men in thesedomains. The score of women stone formers in our samplefor general health was 61.4 � 2.4 compared to 70.6 forhealthy female norms. For bodily pain the scores for women

TABLE 2. Characteris

No. ptsMean pt age � SEMMean kg/m2 BMI � SEM†No. family medical history pos for stones (%)Mean MSC visits from 1/1/1995 (range)No. pts with any stone surgery before 1/1/1996 (%)No. pts with 1 or more surgeries (nonextracorporeal SWL)from 1/1/1996 (%)‡

No. pts with 1 or more extracorporeal SWL from 1/1/1996 (%)No. pts with 1 or more stone related emergency room visits from1/1/2000 (%)

No. comorbidities (%):§Back pain/sciatica�DepressionCoronary artery diseaseDM 2HTNIrritable bowel disease/Crohn’s diseaseMCSOsteoporosis/osteopeniaMore than 1 urinary tract infectionHyperlipidemiaGastroesophageal reflux disease

% Overweight†% Obese†% Normal wt†

* p Values for continuous variables are from 2-sample t tests under the assuin the sample. p Values for discrete variables are from Fisher’s exact test anin the sample.† BMI 18 to 25 characterizes desired or normal weight for height, BMI 25 t

represent 36% of total sample for whom weight and height were available f‡ Median 1.0.§ Comorbidities have a prevalence of 10% or more for any group.� Back pain associated solely with kidney stones was not counted as back

stone formers vs female norms were 66.5 � 2.4 vs 73.6. The

figure is a graphical representation of the scores for alldomains of men and women in our sample compared withthose of healthy men and women.

GenderWithin-sample comparisons and statistical analyses wereperformed to explore differences based on gender, comorbid-ity, number of surgeries, surgery type and other variables.Statistically relevant gender differences were apparent withwomen scoring lower then men in our sample for all domains(transformed scores and 95% confidence intervals for eachdomain are presented in table 4). The differences were mostapparent for physical functioning (p � 0.0092) and vitality(p � 0.0007), for which men and women stone formers

f survey respondents

men Men Whole Group p Value*

100 189� 1.4 52.3 � 1.2 50.9 � 0.94 0.11� 0.78 29.1 � 0.56 29.4 � 0.48 0.65

(42) 41 (41) 78 (41) 1.00(1–11) 3.7 (1–16) 3.5 (1–16) 0.48

(24) 31 (31) 52 (28) 0.33(76) 59 (59) 127 (67) 0.53

(34) 33 (33) 63 (33) 0.69(43) 37 (37) 75 (40) 0.89

(10) 9 (9) 18 (10) 0.81(19) 5 (5) 22 (12) 0.0029(1) 10 (10) 11 (6) 0.011

(12) 7 (7) 18 (10) 0.22(38) 42 (42) 76 (40) 0.66(15) 11 (11) 24 (13) 0.52(28) 12 (12) 37 (20) 0.0061(12) 2 (2) 13 (7) 0.0074(35) 5 (5) 36 (19) �0.0001(22) 31 (31) 51 (27) 0.19(19) 16 (16) 33 (17) 0.70

35 31 0.4533 36 0.6332 33 1.00

n of equal variances, and represent the difference between men and womenresent the difference in prevalence of comorbidity between men and women

epresents overweight and BMI greater than 30 represents obese. NumbersI calculation.

ciatica.

TABLE 3. Health related quality of life scores of stone formersvs healthy U.S. norms

Domain

Mean StoneFormers

Score � SEMU.S. Norms

Score*

Difference Requiredfor Clinical

Significance†

Physical functioning 83.8 � 1.6 84.2 5Role-physical 82.1 � 1.8 81.0 10Bodily pain 69.4‡ � 1.6 75.2 5General health 64.9‡ � 1.6 72.0 5Vitality 59.3 � 1.4 61.0 5Social functioning 85.4 � 1.6 83.3 5Role-emotional 85.4 � 1.5 81.3 10Mental health 74.9 � 1.2 74.7 5

* Scores for U.S. norms are from Ware et al.11

† Criteria for clinically and socially relevant differences, which are domainspecific and sample size dependent, are defined by Ware et al.11

‡ Clinically significant differences from U.S. norms, ie those exceeding the

tics o

Wo

8949.329.8373.4

2168

3038

9171

1134132511312017264034

mptiod rep

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criteria required by Ware et al.11

hin s, soci

HEALTH RELATED QUALITY OF LIFE OF PATIENTS WITH KIDNEY STONES2438

scored 87.7 � 2.0 vs 79.4 � 2.4 and 63.7 � 1.7 vs 54.2 �2.2, respectively. Of these 2 domains only vitality re-mained significantly different between genders in themultivariable analysis (p � 0.0019, table 5). Other statis-tically significant differences between men and women inour sample were shown for role-emotional (p � 0.022),mental health (p � 0.024) and general health (p � 0.049).However, differences for role-emotional and generalhealth were not significant in the multivariable approach.Table 5 tabulates the univariate and multivariable differ-ences for women stone formers for all domains.

ComorbidityResults by comorbidity and BMI revealed differenceswithin the sample (table 5). QOL impairment was accen-tuated among those who were overweight and obese, andamong those with depression, diabetes mellitus, hyper-tension and musculoskeletal complaints. Other comor-bidities (table 2) did not appear to affect QOL scores.Neither the number of stone surgeries nor SWL proce-

Comparison of health related quality of life of male and female s‡, statistically significant differences (p �0.05) determined from 2-sbetween men and women within stone former sample (striped barsWare et al,11 reflecting differences between men and women witrole-physical. BP, bodily pain. GH, general health. VT, vitality. SF

TABLE 4. Health related quality of life scores of menand women within study sample

Domain

Mean Score (95% CI)

p Value*Men Women

Physical functioning 88 (84, 92) 79 (75, 84) 0.0092Role-physical 85 (81, 89) 79 (73, 84) 0.062Bodily pain 72 (68, 76) 66 (62, 71) 0.098General health 68 (64, 72) 61 (57, 66) 0.049Vitality 64 (60, 67) 54 (50, 59) 0.0007Social functioning 88 (84, 92) 82 (77, 88) 0.10Role-emotional 89 (85, 92) 82 (77, 87) 0.022Mental health 77 (74, 80) 72 (68, 76) 0.024

* 2-Sample t tests under the assumption of equal variances.

dures were associated with differences in health relatedQOL (data not shown).

DISCUSSION

In this cross-sectional survey we compared the health profileof patients with stone disease from our clinical practice toU.S. norms. Results indicate that stone formers have lowerhealth related QOL for general health and bodily pain.Women stone formers scored lower against their gendernorms for general health and bodily pain than did malestone formers. Comparisons within our sample showed thatwomen stone formers have clinically and statistically signif-icant lower health related QOL than men for multiple do-mains, more specifically for physical functioning, generalhealth, vitality and mental health.

Comorbidities accentuate impairment in health relatedQOL among stone formers. Overweight and obesity (preva-lence of 66% for men and women in our sample) was associatedwith decrements in physical functioning, role-physical andgeneral health. Diabetes mellitus (type 2) and hypertension,distributed similarly among men and women stone formers,were both associated with reduced health related QOL forphysical functioning and general health. Hypertension wasalso associated with lower scores for role-physical, vitalityand social functioning. The presence of depression and mus-culoskeletal complaints further reduced health related QOLscores, specifically for physical functioning, role-physical,bodily pain, general health and social functioning.

In addition, depression decreased the score for the role-emotional domain, and musculoskeletal complaints wereassociated with a lower score for vitality. Of note, depres-sion and musculoskeletal complaints were unevenly dis-tributed among men and women in our sample. Depres-

formers (striped bars) with respective gender norms (solid bars).e t tests under assumption of equal variance, reflecting differencesclinically significant differences, those that met criteria defined bytone former sample (striped bars). PF, physical functioning. RP,al functioning. RE, role-emotional. MH, mental health.

toneampl). *,

sion prevalence was 19% for women and 5% for men. For

with urolithiasis.

HEALTH RELATED QUALITY OF LIFE OF PATIENTS WITH KIDNEY STONES 2439

musculoskeletal complaints prevalence was 28% vs 12%for women and men, respectively. As more women thanmen had depression and musculoskeletal complaints intheir medical histories, these comorbidities may partiallyexplain the gender differences in health related QOL de-tected within the sample.

Studies of the health related QOL of recurrent stoneformers are needed for several reasons. The acuity of thedisease is driven largely by individual patient percep-tions. Success in the treatment of urolithiasis may not beeradication of the disease but control of patient symptoms,which may improve patient QOL. Patient perceptions areincreasingly recognized as a factor in the quality of uro-logical care. QOL is a primary end point in other clinicalsettings including, but not limited to, those related tocardiac, respiratory, neurological, musculoskeletal andoncological diseases. The health related QOL of patientswith several urological diseases (erectile dysfunction,prostate cancer, urinary continence and overactive blad-der) have been studied.12–14

There are potential limitations to our study. The ret-rospective and cross-sectional design resulted in the in-ability to assess baseline health related QOL of patientsbefore the development of stone disease. Future studiescould address this limitation by assessing and comparingpatients at similar points along the continuum of thedisease. In addition, although study subjects were similarto nonrespondents with respect to age and gender (table1), they may have differed with respect to the complexityor activity of their disease, comorbidities, number of in-terventions, etc. These differences could have influencedthe results. As with other QOL studies, we cannot defin-itively conclude that we measured QOL and not the var-ious effectors of it. Stress, for example, has been proposedto have a role in calcium oxalate urolithiasis15 and symp-tomatic kidney stones.16,17 Stress and other factors, in-cluding psychosocial and socioeconomic elements, arethought to influence QOL.18 Studies could be designed toelucidate the true health related QOL of stone disease vsthat of various other QOL effectors. Finally, as our resultsdescribe patients at a tertiary care center, results fromthis study may not be clearly relevant to patients treatedin the community.

Regardless, we reliably identified impaired health relatedQOL among stone formers, particularly women, comparedwith U.S. norms. Certain comorbidities accentuated the de-creased health related QOL including obesity, DM 2, HTN,depression and MCS. Considering that obesity has beenlinked to uric acid stone disease,19 diabetes mellitus to riskof urosepsis and HTN to renal failure, the importance of thiswork is evident. Reports confirming an increased prevalenceof stones in women further add to the emphasis of thisstudy.20

CONCLUSIONS

Impaired health related QOL was identified in patientswith stones at our metabolic stone center in Wisconsin.The results suggest a need for further studies of thehealth related QOL of stone formers with the aim ofimproving health outcomes. By understanding the health

TABLE 5. Univariate and multivariable regression analyses of theimpact of gender and comorbidities on the health related

quality of life of stone formers

Univariate Multivariable

Beta(effect size) SEM p Value Beta SEM p Value

Physicalfunctioning:Female 8.26 3.14 0.0092 �7.20 5.01 0.16Overweight* 13.62 6.24 0.033 �13.68 6.27 0.033Obese* 16.94 5.99 0.0061 �12.21 5.94 0.044Depression 10.97 4.89 0.026 2.11 6.81 0.76Diabetes† 16.47 5.28 0.0021 �5.94 7.98 0.46HTN* 10.67 3.16 0.0009 �9.36 5.96 0.12MCS‡ 8.41 3.96 0.035 �14.84 5.49 0.0088

Role-physical:Female �6.60 3.52 0.062Overweight* �16.00 7.09 0.027 �15.77 7.15 0.031Obese* �15.06 6.80 0.030 �12.20 6.86 0.080Depression �16.44 5.39 0.0026 �2.08 7.63 0.79Diabetes† �10.20 5.99 0.090HTN �11.40 3.52 0.0014 �7.61 5.99 0.21MCS‡ �14.97 4.33 0.0007 �16.18 6.37 0.014

Bodily pain:Female �5.42 3.26 0.098Overweight* �10.79 7.30 0.14Obese* �14.76 7.00 0.039 �14.25 6.79 0.040Depression �10.86 5.05 0.033 �4.65 7.77 0.55Diabetes† �9.86 5.54 0.077HTN �5.30 3.32 0.11MCS‡ �14.50 3.99 0.0004 �14.89 6.43 0.024

General health:Female �6.53 3.29 0.049 �4.27 3.23 0.19Overweight* �6.98 6.89 0.31Obese* �6.33 6.60 0.34Depression �10.80 5.11 0.036 �2.70 5.09 0.60Diabetes† �18.26 5.48 0.001 �10.24 5.66 0.072HTN �12.99 3.26 <0.0001 �11.14 3.42 0.0014MCS‡ �12.13 4.08 0.0034 �11.01 4.05 0.0072

Vitality:Female �9.52 2.77 0.0007 �8.81 2.80 0.0019Overweight* �5.68 6.13 0.36Obese* �9.12 5.93 0.13Depression �6.63 4.40 0.13Diabetes† �8.71 4.80 0.071HTN �5.86 2.88 0.043 �6.47 2.78 0.021MCS‡ �7.75 3.54 0.030 �5.84 3.50 0.097

Socialfunctioning:Female �5.35 3.28 0.10Overweight* �9.18 7.15 0.20Obese* �3.77 6.86 0.58Depression �17.54 4.97 0.0005 �13.82 5.12 0.0076Diabetes† �3.79 5.60 0.50HTN �7.55 3.32 0.024 �6.66 3.27 0.043MCS‡ �9.82 4.13 0.018 �7.61 4.15 0.068

Role-emotional:Female �6.83 2.95 0.022 �5.11 2.97 0.088Overweight* �7.26 5.78 0.21Obese* �9.24 5.54 0.10Depression �13.97 4.54 0.0024 �12.22 4.63 0.009Diabetes† �7.97 5.05 0.12HTN �4.09 3.03 0.18MCS‡ �5.71 3.74 0.13

Mental health:Female �5.59 2.45 0.024 �5.59 2.45 0.024Overweight* �1.93 4.86 0.69Obese* �4.33 4.66 0.36Depression �7.31 3.83 0.058Diabetes† �6.30 4.20 0.14HTN 0.0012 2.53 1.00MCS‡ �1.68 3.12 0.59

If the univariate analysis was significant (p �0.05), multivariable regres-sion analysis was performed. Data for factors with statistical significanceare shown in bold.* p Values represent the difference from normal weight respondents (BMI

less than 25). Data for factors with statistical significance (p �0.05) areshown in bold.† Refers to type 2 diabetes only.‡ Musculoskeletal complaints independent of complaints associated solely

related QOL of patients with urolithiasis, clinicians may

HEALTH RELATED QUALITY OF LIFE OF PATIENTS WITH KIDNEY STONES2440

better understand the differential effects of the disease onpatients’ lives.

Abbreviations and Acronyms

BMI � body mass indexDM 2 � diabetes mellitus type 2HTN � hypertensionMCS � musculoskeletal complaintsMSC � Metabolic Stone ClinicQOL � quality of lifeSWL � shock wave lithotripsy

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19. Ekeruo WO, Tan YH, Young MD, Dahm P, Maloney ME,Mathias BM et al: Metabolic risk factors and the impact ofmedical therapy on the management of nephrolithiasis inobese patients. J Urol 2004; 172: 159.

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EDITORIAL COMMENT

In what is arguably the first methodologically rigorous as-sessment of quality of life in patients with recurrent uroli-thiasis, the authors have definitively confirmed that kidneystones are associated with bodily pain. Although men bearabout twice the stone burden as women in health care use,the authors showed in multivariate analyses that womenstone formers bear the greater human cost when measuredas patient centered health outcomes (reference 2 in article).This report confirms in stone formers the well establishedgeneral observation that women score worse than menacross the domains of the SF-36.1 That these quality of lifeimpairments are magnified in individuals with depression,diabetes, musculoskeletal disease or obesity is consistentwith the extensive literature on patient reported outcomesand comorbidity (www.sf-36.org and www.proqolid.org). Asthe authors acknowledge, this work serves as a solid descrip-tive foundation on which to base hypothesis driven research.

Mark S. LitwinDepartment of Urology

David Geffen School of Medicine at UCLALos Angeles, California

1. McHorney CA, Ware JE Jr, Lu JF and Sherbourne CD: TheMOS 36-item Short-Form Health Survey (SF-36): III. Testsof data quality, scaling assumptions, and reliability across

diverse patient groups. Med Care 1994; 32: 40.