Urolithiasis DOI 10.1007/s00240-015-0773-5
REVIEW
Diabetes mellitus and the risk of urolithiasis: a meta‑analysis of observational studies Lu Hao Liu1 · Ran Kang1 · Jun He1 · Shan Kun Zhao1 · Fu Tian Li1 · Zhi Gang Zhao1
Received: 3 February 2015 / Accepted: 8 April 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Diabetes mellitus (DM) might increase the risk of urolithiasis, but the results were inconsistent. Hence, we conducted a meta-analysis to assess the association between DM and the risk of urolithiasis. We searched PubMed, Embase, and Cochrane Library to identify the relevant observational studies up to November 2014. Reference lists of retrieved articles were also reviewed. Summary relative risks (RRs) and corresponding 95 % confidence intervals (CIs) were used to estimate the association between DM and the risk of urolithiasis. We identified 3 case–control studies and 4 cohort studies regarding DM and the risk of urolithiasis, involving 247,531 participants. Analyses of all studies showed that DM was associated with an increased risk of urolithiasis (RR = 1.24, 95 % CI: 1.14– 1.35). There was heterogeneity among studies (p = 0.027,
I2 = 57.9 %). The association between DM and the risk of urolithiasis was not significantly differed by gender, but this association was inconsistent in the North American and Asian populations. When restricting the analysis to studies that had adjusted for body mass index (n = 2) or hypertension (n = 3), the RRs were 1.46 (95 % CI: 1.03–2.06) and 1.22 (95 % CI: 1.01–1.48), respectively. There was no significant publication bias (p = 0.96 for Egger’s regression asymmetry test). Our study provided evidence that there was a significant direct association of DM and the risk of urolithiasis. However, this finding was based on the observational studies, and more well-designed randomized controlled trials were needed. Keywords Diabetes mellitus · Urolithiasis · Meta-analysis
L. H. Liu and R. Kang have contributed equally to this work. * Zhi Gang Zhao [email protected] Lu Hao Liu [email protected] Ran Kang [email protected] Jun He [email protected] Shan Kun Zhao [email protected] Fu Tian Li [email protected] 1
Guangdong Provincial Key Laboratory of Urology, Department of Urology and Andrology, Minimally Invasive Surgery Center, The First Affiliated Hospital of Guangzhou Medical University, No. 1‑3, Kangda Road, 510230 Guangzhou, Guangdong Province, China
Introduction Urolithiasis is a painful and common disease. It poses a significant health care burden in a working age population [1]. There has been a marked increase in the prevalence and incidence of urolithiasis in the USA and worldwide over the past several decades [2, 3]. Environmental factors, such as dietary habits and lifestyle factors, likely play an important role in the changing epidemiology of urolithiasis [4]. However, other independent risk factors are not clearly known, and the pathogenesis of urolithiasis needs to be further explored. Diabetes mellitus (DM) is considered to be one of the major public health challenges in many Asian countries and in many other industrialized nations [5, 6]. DM is associated with long-term complications that include a variety of cancers, cardiovascular disease, retinopathy, neuropathy,
13
Urolithiasis
and nephropathy [7–10]. And DM is also known to influence risk of stone formation [11]. Diabetes may be a risk factor for urolithiasis, but findings from epidemiological studies are inconsistent [3, 12–24]. To our knowledge, there is currently no available comprehensive analysis of available studies of DM and urolithiasis using a systematic approach and accounting for their specificities. We performed a meta-analysis of all eligible observational studies to derive a more precise estimation of the relationship between DM and risk of urolithiasis.
Materials and methods Literature and search strategy Studies were identified by searching electronic databases and scanning reference lists of articles. The PubMed, Embase and Cochrane Library were searched systematically for studies published from inception until November 1,2014, using a combination of search terms related to diabetes (“diabetes mellitus”, “type 2 diabetes”, “hyperglycemia”) and to urolithiasis (“urinary calculi”, “urinary tract calculi”, “urinary stone disease”, “nephrolithiasis”, “urinary tract stones”, “kidney stones”). This search strategy was performed iteratively until no new relevant articles were found. The searches were restricted to publications in English. Study selection Case–control and cohort studies reporting a quantitative measure of the association between exposure to diabetes and risk of urolithiasis were eligible. Studies conducted among individuals with metabolic syndrome or gestational diabetes, or without the raw data of the number of DM and events were excluded. Case reports, editorials, animal studies and review articles should not be included in this meta-analysis. If the publications were duplicated or shared in more than one study, either the most recent or complete publication was included. Data extraction Two investigators independently extracted the data using standardized extraction forms according to the meta-analysis of observational studies in epidemiology (MOOSE) guidelines [25]. Disagreements were resolved by consensus or, when necessary, by the third investigator. We extracted any reported odds ratios (ORs), relative risks (RRs), hazard ratios, or incidence density ratios of outcomes for patients with urolithiasis compared with the reference group. We also extracted study characteristics for each article. The
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following information was sought from each study: the first author’s last name, year of publication, country of study location, study design, numbers of cases and controls (in case–control studies), number of exposed and unexposed (in cohort studies), duration of follow-up, risk of estimates with their corresponding confidence intervals (CIs) for urolithiasis associated with DM, and statistical adjustments for confounding factors. Statistical analysis We summarized extracted data in tables and performed a narrative synthesis of all the included studies. RR was used as a common measure of the association between DM and risk of urolithiasis. If multivariate RRs were provided, they were used for statistical analysis in preference to the univariate RRs. To assess for heterogeneity between studies, we calculated the Cochran Q statistic with significance level of p
REVIEW
Diabetes mellitus and the risk of urolithiasis: a meta‑analysis of observational studies Lu Hao Liu1 · Ran Kang1 · Jun He1 · Shan Kun Zhao1 · Fu Tian Li1 · Zhi Gang Zhao1
Received: 3 February 2015 / Accepted: 8 April 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Diabetes mellitus (DM) might increase the risk of urolithiasis, but the results were inconsistent. Hence, we conducted a meta-analysis to assess the association between DM and the risk of urolithiasis. We searched PubMed, Embase, and Cochrane Library to identify the relevant observational studies up to November 2014. Reference lists of retrieved articles were also reviewed. Summary relative risks (RRs) and corresponding 95 % confidence intervals (CIs) were used to estimate the association between DM and the risk of urolithiasis. We identified 3 case–control studies and 4 cohort studies regarding DM and the risk of urolithiasis, involving 247,531 participants. Analyses of all studies showed that DM was associated with an increased risk of urolithiasis (RR = 1.24, 95 % CI: 1.14– 1.35). There was heterogeneity among studies (p = 0.027,
I2 = 57.9 %). The association between DM and the risk of urolithiasis was not significantly differed by gender, but this association was inconsistent in the North American and Asian populations. When restricting the analysis to studies that had adjusted for body mass index (n = 2) or hypertension (n = 3), the RRs were 1.46 (95 % CI: 1.03–2.06) and 1.22 (95 % CI: 1.01–1.48), respectively. There was no significant publication bias (p = 0.96 for Egger’s regression asymmetry test). Our study provided evidence that there was a significant direct association of DM and the risk of urolithiasis. However, this finding was based on the observational studies, and more well-designed randomized controlled trials were needed. Keywords Diabetes mellitus · Urolithiasis · Meta-analysis
L. H. Liu and R. Kang have contributed equally to this work. * Zhi Gang Zhao [email protected] Lu Hao Liu [email protected] Ran Kang [email protected] Jun He [email protected] Shan Kun Zhao [email protected] Fu Tian Li [email protected] 1
Guangdong Provincial Key Laboratory of Urology, Department of Urology and Andrology, Minimally Invasive Surgery Center, The First Affiliated Hospital of Guangzhou Medical University, No. 1‑3, Kangda Road, 510230 Guangzhou, Guangdong Province, China
Introduction Urolithiasis is a painful and common disease. It poses a significant health care burden in a working age population [1]. There has been a marked increase in the prevalence and incidence of urolithiasis in the USA and worldwide over the past several decades [2, 3]. Environmental factors, such as dietary habits and lifestyle factors, likely play an important role in the changing epidemiology of urolithiasis [4]. However, other independent risk factors are not clearly known, and the pathogenesis of urolithiasis needs to be further explored. Diabetes mellitus (DM) is considered to be one of the major public health challenges in many Asian countries and in many other industrialized nations [5, 6]. DM is associated with long-term complications that include a variety of cancers, cardiovascular disease, retinopathy, neuropathy,
13
Urolithiasis
and nephropathy [7–10]. And DM is also known to influence risk of stone formation [11]. Diabetes may be a risk factor for urolithiasis, but findings from epidemiological studies are inconsistent [3, 12–24]. To our knowledge, there is currently no available comprehensive analysis of available studies of DM and urolithiasis using a systematic approach and accounting for their specificities. We performed a meta-analysis of all eligible observational studies to derive a more precise estimation of the relationship between DM and risk of urolithiasis.
Materials and methods Literature and search strategy Studies were identified by searching electronic databases and scanning reference lists of articles. The PubMed, Embase and Cochrane Library were searched systematically for studies published from inception until November 1,2014, using a combination of search terms related to diabetes (“diabetes mellitus”, “type 2 diabetes”, “hyperglycemia”) and to urolithiasis (“urinary calculi”, “urinary tract calculi”, “urinary stone disease”, “nephrolithiasis”, “urinary tract stones”, “kidney stones”). This search strategy was performed iteratively until no new relevant articles were found. The searches were restricted to publications in English. Study selection Case–control and cohort studies reporting a quantitative measure of the association between exposure to diabetes and risk of urolithiasis were eligible. Studies conducted among individuals with metabolic syndrome or gestational diabetes, or without the raw data of the number of DM and events were excluded. Case reports, editorials, animal studies and review articles should not be included in this meta-analysis. If the publications were duplicated or shared in more than one study, either the most recent or complete publication was included. Data extraction Two investigators independently extracted the data using standardized extraction forms according to the meta-analysis of observational studies in epidemiology (MOOSE) guidelines [25]. Disagreements were resolved by consensus or, when necessary, by the third investigator. We extracted any reported odds ratios (ORs), relative risks (RRs), hazard ratios, or incidence density ratios of outcomes for patients with urolithiasis compared with the reference group. We also extracted study characteristics for each article. The
13
following information was sought from each study: the first author’s last name, year of publication, country of study location, study design, numbers of cases and controls (in case–control studies), number of exposed and unexposed (in cohort studies), duration of follow-up, risk of estimates with their corresponding confidence intervals (CIs) for urolithiasis associated with DM, and statistical adjustments for confounding factors. Statistical analysis We summarized extracted data in tables and performed a narrative synthesis of all the included studies. RR was used as a common measure of the association between DM and risk of urolithiasis. If multivariate RRs were provided, they were used for statistical analysis in preference to the univariate RRs. To assess for heterogeneity between studies, we calculated the Cochran Q statistic with significance level of p
