In a cross-over trial of subjects with suspected NCGS, the severity of overall symptoms increased significantly during 1 week of intake of small amounts of gluten, compared with placebo. Clinical trial no: ISRCTN72857280.

According to the per-protocol analysis of data from the 59 patients who completed the trial, intake of gluten significantly increased overall symptoms compared with placebo (P = .034). Abdominal bloating (P = .040) and pain (P = .047), among the intestinal symptoms, and foggy mind (P = .019), depression (P = .020), and aphthous stomatitis (P = .025), among the extraintestinal symptoms, were significantly more severe when subjects received gluten than placebo.

We enrolled 61 adults without celiac disease or a wheat allergy who believed ingestion of gluten-containing food to be the cause of their intestinal and extraintestinal symptoms. Participants were assigned randomly to groups given either 4.375 g/day gluten or rice starch (placebo) for 1 week, each via gastrosoluble capsules. After a 1-week gluten-free diet, participants crossed over to the other group. The primary outcome was the change in overall (intestinal and extraintestinal) symptoms, determined by established scoring systems, between gluten and placebo intake. A secondary outcome was the change in individual symptom scores between gluten vs placebo.

There is debate over the existence of nonceliac gluten sensitivity (NCGS) intestinal and extraintestinal symptoms in response to ingestion of gluten-containing foods by people without celiac disease or wheat allergy. We performed a randomized, double-blind, placebo-controlled, cross-over trial to determine the effects of administration of low doses of gluten to subjects with suspected NCGS.

Gluten sensitivity was defined by an international panel as the occurrence of intestinal and extraintestinal symptoms related to the ingestion of gluten-containing food in subjects without wheat allergy or celiac disease.Nonceliac gluten sensitivity (NCGS) now is considered a more proper term to distinguish this condition from celiac disease.

NCGS has raised considerable interest and debate in both the medical and nonmedical literature. Public awareness of NCGS is higher than that of celiac disease,and crowded online forums continually guide patients to eventually reach their own self-diagnosis.Nevertheless, the very existence of NCGS as a discrete entity was questioned,and in the absence of intestinal lesions, specific antibodies, or any other biomarker, the absolute need for an optimal diagnostic algorithm and shared diagnostic criteria was reiterated.Most of the information on NCGS, such as its high prevalence,activation of the innate immunity as a preferential pathogenic mechanism,existence of a specific mucosal cytokine profile,and its clinical spectrum,was obtained from patients who mainly are self-reported to be gluten-sensitive. Because at present nobody knows how many of these patients really are affected by NCGS, we performed a double-blind, placebo-controlled, cross-over, gluten-challenge trial of patients suspected of having NCGS.

A per-protocol approach was applied for this cross-over trial, and the statistical analysis was conducted on patients with available data in both study periods (2 patients were excluded owing to missing data, see later). The determination of the sample size was made by using a 2-sided testing framework with an α error of .05 and a β error of .2, because the prospective primary hypothesis was that the 1-week treatment with gluten would result in a different severity of the overall score, as assessed by the sum of intestinal and extraintestinal scores, than the 1-week treatment with placebo. Assuming a within-patient comparison and a SD of the overall score of 40, we estimated that 58 patients would be needed to achieve a power of 80%, at a 2-sided 5% significance level, if the true difference was 15. An analysis of variance (ANOVA) for cross-over design was conducted (see the Supplementary Methods section).

The primary outcome was the change in the weekly overall symptom score, as assessed by the sum of the intestinal and extraintestinal scores, between the 1-week treatment with gluten and the 1-week treatment with placebo. Patients were asked to grade 15 intestinal symptoms and 13 extraintestinal symptoms daily (see the Supplementary Methods section).Secondary outcomes were as follows: (1) the change in individual symptom scores between 1-week treatment with gluten and 1-week treatment with placebo, (2) the identification of patients with true NCGS, and (3) to verify whether laboratory parameters at baseline might be predictive of true NCGS. True NCGS patients were defined as having a delta overall score—calculated by subtracting the weekly overall score while taking the placebo from the score while taking gluten—higher than the mean delta overall score +2 SD, at the end of the trial. Laboratory parameters included serum IgG antigliadin antibodies (AGA), fecal calprotectin, HLA genotyping, and intraepithelial lymphocyte density (see the Supplementary Methods section).

Patients were randomized according to a computer-generated list of random numbers held by an independent observer to either the gluten or the placebo treatment group ( Figure 2 ). Patients were asked to fill in a daily questionnaire to assess a rating scale of both intestinal and extraintestinal symptoms (see the Supplementary Methods section) over a 5-week period. Participants were asked to follow a strict gluten-free diet (GFD) starting 1 week before the randomization (week 0 [W]) and continuing until the end of the study period (W). Compliance with the GFD was assessed by using a validated questionnaire.At W, patients were given either gastrosoluble capsules containing purified wheat gluten (10 capsules ingested on no more than 2 occasions over the day, corresponding to a daily gluten intake of 4.375 g, equivalent to ∼2 slices of white bread) or gastrosoluble capsules containing rice starch (10 capsules corresponding to a daily rice starch intake of 4.375 g) as placebo for 1 week. Rice starch was chosen as the placebo because it is the most readily absorbable of the complex carbohydrates, and thus less fermentable, in the intestinal tract.At the end of the first treatment week, patients from both arms continued only their wash-out from gluten, without taking any capsule. Subsequently, at Windividuals belonging to the first arm were given placebo capsules, and individuals belonging to the second arm were given gluten capsules. After the second treatment week, all patients continued with their wash-out from gluten. Capsules were kindly provided by Giuliani Pharma (Milan, Italy).

A total of 118 adult patients were referred consecutively between October 2012 and November 2013 to 2 Italian Celiac Centers (Pavia and Bologna) because of the persistence of relevant intestinal and extraintestinal symptoms believed by themselves to be caused by food containing even low doses of gluten, such as a sandwich or 2 slices of white bread, and affecting their quality of life. Only 92 patients, all on a gluten-containing diet at the time of screening for at least 2 months, underwent ad hoc screening ( Figure 1 and the Supplementary Methods section). Among them, 61 patients (39 enrolled in Pavia and 22 in Bologna) were randomized in the trial ( Table 1 ).

The study was a prospective, randomized, placebo-controlled, cross-over trial that compared the effects of a daily dose of 4.375 g gluten with placebo in patients strongly suspected of having NCGS. The patients and the physicians who administered the interventions were blinded. Enrollment started in September 2012, and follow-up evaluation was completed in January 2014. The Ethics Committee at both clinical sites (Pavia and Bologna) approved the study (trial registration number: ISRCTN72857280; http://www.controlled-trials.com/ISRCTN72857280 ), and patients provided written informed consent. All authors had access to the study data and have reviewed and approved the final manuscript.

Finally, we analyzed laboratory parameters, such as serum IgG AGA, fecal calprotectin, intraepithelial lymphocyte density, and HLA genotyping, all assessed at baseline and while ingesting the gluten-containing diet (see Supplementary Methods ).

A further secondary end point of the study was to analyze individual symptoms. Regarding intestinal symptoms, 2 among the 15 investigated (ie, abdominal bloating [P = .040] and abdominal pain [P = .047]) were worsened significantly by gluten in comparison with placebo ( Figure 3 B and C). Abdominal pain and bloating were the most scored intestinal symptoms over the week receiving gluten, followed by wind ( Supplementary Table 1 ). Regarding extraintestinal symptoms, 3 among the 13 investigated (ie, foggy mind [P = .019], depression [P = .020], and aphthous stomatitis [P = .025]) were worsened significantly by gluten in comparison with placebo ( Figure 3 D and E). Among the 3 extraintestinal symptoms that were worsened significantly by gluten, only foggy mind was among the most scored extraintestinal symptoms during the gluten week ( Supplementary Table 2 ). When we assessed the percentages of patients complaining of individual symptoms while receiving gluten, we observed that among the 5 most prevalent symptoms, 3 were intestinal (abdominal pain, bloating, and wind), and 2 were extraintestinal (headache and tiredness) ( Supplementary Table 3 ). A significant positive correlation was found between symptom prevalence and overall score while ingesting gluten both for intestinal (r= 0.92; P < .0001) and extraintestinal symptoms (r= 0.90; P < .0001). None of the intestinal or extraintestinal symptoms showed higher mean scores while ingesting placebo compared with gluten.

When we plotted the weekly overall score while ingesting gluten (X-axis) and the weekly overall score while ingesting the placebo (Y-axis) in an XY-diagram for each subject, we observed that most of the patients (44 of 59; 74%) clustered in a squared area defined by an overall score of less than 90, while ingesting both gluten and placebo ( Figure 4 A). Among the 44 patients contained in the squared area, 31 (those in the grey hexagonal area) were very close to the dashed diagonal line (ie, they complained to an equal degree of overall symptoms while ingesting either gluten or placebo). Our attention conversely was focused on the 9 patients (15%) localized in the lower right region of the diagram, that is, those patients strongly suspected to be true gluten-sensitive according to their high positive gap between gluten and placebo scores. Thus, we plotted patients on the basis of their delta overall scores, which ranged from -103 to +156, with a mean value of 12.2 (SD, 50.4) ( Figure 4 B, dashed line). According to our definition (mean, +2 SD), the cut-off level of the overall delta score was +113 (dotted line). Only 3 patients had an overall delta score greater than 113, and thus were identified as true gluten-sensitive. Of note, these 3 patients ( Figure 4 B, grey ellipse) were 3 of the 4 patients who clustered in the lower-right region of the XY-diagram in Figure 4 A (grey ellipse). We also analyzed the intestinal score ( Supplementary Figure 1 ) and the extraintestinal score ( Supplementary Figure 2 ) separately, and we obtained results comparable with those derived from the analysis of the overall score. In particular, 8 patients (13%) had a worsening of intestinal symptoms while ingesting gluten because they were localized in the lower right region of the diagram ( Supplementary Figure 1 B), and 6 patients (10%) had a worsening of extraintestinal symptoms while ingesting gluten ( Supplementary Figure 2 B).

(A) Distribution of patients according to their weekly gluten and placebo overall scores. The closer patients are to the dashed diagonal line, the more comparable their degrees of response are to either gluten or placebo. The squared area incorporates patients experiencing mild degrees of overall response (<90) either with gluten or placebo (44 of 59). Most of them (31 of 44) had comparable overall scores either with gluten or placebo (grey hexagonal area). (B) Distribution of patients according to their weekly overall delta score, calculated by subtracting the overall score while on placebo from that ingesting gluten. The mean (SD) weekly overall delta score was 12.2 (50.4) (dashed line). Only 3 patients had an overall delta score higher than the fixed cut-off value (mean + 2 SD, 113). These 3 patients (grey ellipse) were 3 of the 4 patients who clustered in the lower-right region of the diagram in panel A (grey ellipse).

Figure 4 (A) Distribution of patients according to their weekly gluten and placebo overall scores. The closer patients are to the dashed diagonal line, the more comparable their degrees of response are to either gluten or placebo. The squared area incorporates patients experiencing mild degrees of overall response (<90) either with gluten or placebo (44 of 59). Most of them (31 of 44) had comparable overall scores either with gluten or placebo (grey hexagonal area). (B) Distribution of patients according to their weekly overall delta score, calculated by subtracting the overall score while on placebo from that ingesting gluten. The mean (SD) weekly overall delta score was 12.2 (50.4) (dashed line). Only 3 patients had an overall delta score higher than the fixed cut-off value (mean + 2 SD, 113). These 3 patients (grey ellipse) were 3 of the 4 patients who clustered in the lower-right region of the diagram in panel A (grey ellipse).

According to the per-protocol analysis of the 59 patients who completed the trial, the 1-week treatment with gluten resulted in a significantly (P = .034) higher severity of the overall score in comparison with the 1-week treatment with placebo ( Table 2 ). The median overall score after 1 week of gluten consumption was 48 (range, 1–156), whereas after 1 week of placebo the score was 34 (range, 0–178). However, when we applied the ANOVA for cross-over design, the overall score of the 59 patients in the first week (W–W) (median, 50; range, 2–178) was significantly (P = .009) higher in comparison with that observed in the second week (W–W) (median, 33; range, 0–155) ( Table 2 ). No significant difference (P = .242) was found in the overall score between sequences (ie, gluten→placebo and placebo→gluten). The daily overall score over the gluten/placebo treatment week is shown in Figure 3 A. At day 0 no significant difference was found in the mean overall score between the 2 subgroups of patients who had experienced or had not experienced a self-prescribed GFD.

Comparison of the scores of overall symptoms in the gluten- and placebo-treated groups during (A) 1 week of treatment, and comparison of scores of the (B and C) intestinal and (D–F) extraintestinal symptoms that were worsened significantly by gluten. The data shown represent the mean overall score (±SEM) from each day.

Figure 3 Comparison of the scores of overall symptoms in the gluten- and placebo-treated groups during (A) 1 week of treatment, and comparison of scores of the (B and C) intestinal and (D–F) extraintestinal symptoms that were worsened significantly by gluten. The data shown represent the mean overall score (±SEM) from each day.

Mean and Median Values of the Weekly Overall Symptom Score by Treatment, Period, and Sequence in the 59 Patients Who Completed the Study

Table 2 Mean and Median Values of the Weekly Overall Symptom Score by Treatment, Period, and Sequence in the 59 Patients Who Completed the Study

According to the cross-over trial design, 31 patients (arm 1) started with gluten capsules in the first treatment week (W–W), followed by placebo capsules in the second week (W–W), whereas 30 patients (arm 2) started with placebo capsules in the first treatment week, followed by gluten capsules in the second week ( Figure 2 ). Baseline characteristics were similar between the groups ( Table 1 ). Fifty-nine of the 61 randomized patients completed the 5-week trial as per protocol, 2 patients discontinued the study prematurely because of intolerable symptoms ( Figure 1 ): 1 patient withdrew after 2 days of the first treatment week (arm 2, placebo) because of abdominal pain and nausea, and 1 patient withdrew after 2 days of the first treatment week (arm 1, gluten) because of abdominal pain and diarrhea.

Discussion

17 Wieser H. Chemistry of gluten proteins. 18 Di Sabatino A.

Corazza G.R. Coeliac disease. 19 Di Sabatino A.

Biagi F.

Giuffrida P.

Corazza G.R. The spectrum of gluten-related disorders. 20 Doherty M.

Barry R.E. Gluten-induced mucosal changes in subjects without overt small-bowel disease. Gluten proteins are among the most complex protein systems owing to numerous components of various sizes, and owing to further variability determined by genotype, growing conditions, and technologic processes.The complexity of the gluten structure couples with the multifaceted pathologic and clinical spectrum of gluten-related conditions that, in addition to celiac disease,include wheat allergy and a number of extraintestinal disorders.Moreover, gluten administration for long periods or in high doses can cause symptoms and intestinal lesions in unaffected relatives of celiac patients and in nonceliac individuals with altered immunity.

2 Di Sabatino A.

Corazza G.R. Nonceliac gluten sensitivity: sense or sensibility?. NCGS, a possible further example of this complexity, has been attracting increasing attention in recent years. A growing number of patients claim that gluten is responsible for both intestinal and extraintestinal symptoms to an extent that impairs their quality of life. On this basis, self-prescription of gluten withdrawal is becoming increasingly common, but this behavior should be strongly discouraged because it may lead to the consequent preclusion of a proper diagnosis of celiac disease and to a high and unjustified economic burden.Because a reliable marker of NCGS is not readily available at present, double-blind, placebo-controlled trials are mandatory to ascertain this condition.

21 Biesiekierski J.R.

Newnham E.D.

Irving P.M.

et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. , 22 Biesiekierski J.R.

Peters S.L.

Newnham E.D.

et al. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. , 23 Vazquez-Roque M.I.

Camilleri M.

Smyrk T.

et al. A controlled trial of gluten-free diet in patients with irritable bowel syndrome-diarrhea: effects on bowel frequency and intestinal function. 24 Klein K.B. Controlled treatment trials in the irritable bowel syndrome: a critique. , 25 Spiller R.C. Problems and challenges in the design of irritable bowel syndrome clinical trials: experience from published trials. Unlike previous prospective, double-blind, placebo-controlled, gluten-challenge trials,the topic of this study is not the patients referred for irritable bowel syndrome based on Rome III criteria, but patients referred to tertiary centers because of intestinal and extraintestinal symptoms caused by the ingestion of even low doses of gluten. To overcome the most common biases linked to double-blind, placebo-controlled trials,we adopted a number of anticipatory measures, including the pretesting demonstration that gluten capsules were indistinguishable from placebo capsules in taste and appearance, the exclusion of patients reporting minimal symptoms, and the choice as the primary end point of change in the global response, which is what patients definitely want to improve. Specific changes in bowel habits or single extraintestinal symptoms might not reflect the complexity of such a polymorphic syndrome. On the other hand, because global measures may miss some specific effects, we also analyzed the influence of gluten on single intestinal and extraintestinal symptoms.

22 Biesiekierski J.R.

Peters S.L.

Newnham E.D.

et al. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. , 26 Gibson P.R.

Shepherd S.J. Food choice as a key management strategy for functional gastrointestinal symptoms. , 27 Welch R.W.

Antoine J.M.

Berta J.L.

et al. Guidelines for the design, conduct and reporting of human intervention studies to evaluate the health benefits of foods. 25 Spiller R.C. Problems and challenges in the design of irritable bowel syndrome clinical trials: experience from published trials. Further guarantors of the validity of this study are the good level of patient compliance to both treatments and GFD, carefully verified throughout the trial, the lack of carry-over effects shown by the absence of a significant difference in the mean overall score between sequences, and the low rate of patient withdrawal. Nevertheless, we observed an order effect, shown by the significant difference in the mean overall score between periods (period 1 over period 2), which was present regardless of the nature of the treatment. This effect, which is unavoidable in cross-over trials,is a well-known consequence of the psychological impact of entering into a trial.

21 Biesiekierski J.R.

Newnham E.D.

Irving P.M.

et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. , 22 Biesiekierski J.R.

Peters S.L.

Newnham E.D.

et al. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. , 28 Cooper B.T.

Holmes G.K.

Ferguson R.

et al. Gluten-sensitive diarrhea without evidence of celiac disease. 22 Biesiekierski J.R.

Peters S.L.

Newnham E.D.

et al. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. 29 Leffler D.

Schuppan D.

Pallav K.

et al. Kinetics of the histological, serological and symptomatic responses to gluten challenge in adults with coeliac disease. 30 Anderson I.H.

Levine A.S.

Levitt M.D. Incomplete absorption of the carbohydrate in all-purpose wheat flour. 21 Biesiekierski J.R.

Newnham E.D.

Irving P.M.

et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. 25 Spiller R.C. Problems and challenges in the design of irritable bowel syndrome clinical trials: experience from published trials. In the present study, gluten was tested in a daily dose considerably lower than that administered in previous double-blind, placebo-controlled trials (16–20 g),but certainly more physiologic (4.375 g are roughly equivalent to 1 sandwich or 2 slices of wheat bread), and still able to induce either symptoms in NCGS patientsor small-bowel lesions in celiac patients.Moreover, it should be underlined that higher gluten doses may evoke nonspecific effects on gastrointestinal fermentationor motility in normal subjects (unpublished data). Based on the observations of Biesiekierski et al,who found that symptoms appeared in the first 7 days after starting gluten administration, we believed a 1-week exposure to gluten to be sufficient. In addition, longer treatment periods are supposed to be burdened by higher nonadherence rates,which, surprisingly, were not reported by other longer gluten-challenge trials. A possible limitation of our study was the relatively short period of wash-out from gluten. However, the low mean overall score at day 0 for all the patients, and the lack of a significant difference in the mean overall score at day 0 between the 2 subgroups of patients who had experienced or not a self-prescribed GFD, indicated that a 1-week wash-out from gluten was enough to neutralize gluten-dependent symptom complaints during the baseline gluten-containing diet.

31 Suarez F.L.

Savaiano D.A.

Levitt M.D. A comparison of symptoms after the consumption of milk or lactose-hydrolyzed milk by people with self-reported severe lactose intolerance. , 32 Jewett D.L.

Fein G.

Greenberg M.H. A double-blind study of symptom provocation to determine food sensitivity. We found that the overall symptom score was significantly higher while ingesting gluten in comparison with placebo. However, when we examined the individual patients’ overall scores we found that only a minority of the participants experienced a real worsening of symptoms while ingesting gluten. Although it is possible that the global evaluation of the symptoms may in some way have attenuated the effect played by gluten on predominant symptoms (ie, abdominal bloating and pain), we do acknowledge that the relevance of NCGS should be reappraised. This view also was supported by the evidence that in the vast majority of patients the clinical weight of gluten-dependent symptoms was irrelevant in light of the comparable degree of symptoms experienced with placebo. If we look at the distribution of overall delta scores (gluten minus placebo), it is not surprising to note that a fair number of patients were victims of the nocebo effect, which was proved extensively through double-blind, placebo-controlled trials.

21 Biesiekierski J.R.

Newnham E.D.

Irving P.M.

et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. , 22 Biesiekierski J.R.

Peters S.L.

Newnham E.D.

et al. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. 11 Volta U.

Bardella M.T.

Calabrò A.

et al. An Italian prospective multicenter survey on patients suspected of having non-celiac gluten sensitivity. , 12 Aziz I.

Lewis N.R.

Hadjivassiliou M.

et al. A UK study assessing the population prevalence of self-reported gluten sensitivity and referral characteristics to secondary care. , 13 Biesiekierski J.R.

Newnham E.D.

Shepherd S.J.

et al. Characterization of adults with a self-diagnosis of nonceliac gluten sensitivity. In keeping with previous studies,we found that both abdominal pain and bloating were worsened significantly by gluten. Moreover, both of these symptoms were the most scored during the gluten treatment week, and the most prevalent among all the participants in the trial. This was quite an interesting finding when considering the results of recent surveys conducted on large cohorts of patients merely suspected of having NCGS, showing that abdominal pain and bloating are a complaint in up to 80% of patients.

33 Peters S.L.

Biesiekierski J.R.

Yelland G.W.

et al. Randomised clinical trial: gluten may cause depression in subjects with non-coeliac gluten sensitivity - an exploratory clinical study. Among the extraintestinal symptoms, foggy mind, depression, and aphthous stomatitis were worsened significantly by gluten, although unlike intestinal symptoms they were not among the most scored symptoms during the 1-week treatment with gluten. The observation that short-term exposure to gluten induced depression is remarkable, and this result was supported by a recent double-blind, placebo-controlled, cross-over study in which depression was assessed by an ad hoc psychiatric score.The direct highly significant correlation between symptom score and symptom prevalence at both the intestinal and extraintestinal levels is indirect proof of the validity of our findings.

We acknowledge that our study did not provide any progress in identifying possible biomarkers of NCGS, neither serum IgG AGA nor intraepithelial lymphocytes correlated with either the overall response to gluten or the overall delta score, and in clarifying the pathogenic mechanisms underlying NCGS. Experiments aimed at defining the cytokine milieu in the duodenal mucosa of the patients enrolled in this trial are being conducted in our laboratory, and preliminary data do not seem to support the involvement of either innate or adaptive immune mechanisms in this condition.

In conclusion, in the present trial, most patients showed approximately equal degrees of overall symptoms with either gluten or placebo, although overall symptoms were worsened significantly by gluten in comparison with placebo. Regarding the identification of the true gluten-sensitive patients, it should be interpreted cautiously because of the lack of a control group of non–gluten-sensitive subjects, and it does not represent crucial evidence in favor of the existence of this new syndrome. We cannot exclude the possibility that these patients merely had increased visceral or extraintestinal hypersensitivity to gluten, or that higher gluten doses could have shown a larger cohort of sensitive patients. A greater understanding of the gut/gluten relationship probably can be obtained by dissecting the mechanisms driven by the administration of gluten in healthy volunteers.