Stephen T. Amann

Alcohol and Smoking as Risk Factors in an Epidemiology Study of Patients With Chronic Pancreatitis

BACKGROUND & AIMS Alcohol has been implicated in the development of chronic pancreatitis (CP) in 60%-90% of patients, although percentages in the United States are unknown. We investigated the epidemiology of alcohol-related CP at tertiary US referral centers. METHODS We studied data from CP patients (n = 539) and controls (n = 695) enrolled in the North American Pancreatitis Study-2 from 2000 to 2006 at 20 US referral centers. CP was defined by definitive evidence from imaging or histologic analyses. Subjects and physicians each completed a study questionnaire. Using physician-assigned diagnoses, patients were assigned to an etiology group: alcohol (with/without other diagnoses), nonalcohol (any etiology of CP from other than alcohol), or idiopathic (no etiology identified). RESULTS The distribution of patients among etiology groups was: alcohol (44.5%), nonalcohol (26.9%), and idiopathic (28.6%). Physicians identified alcohol as the etiology more frequently in men (59.4% men vs 28.1% women), but nonalcohol (18% men vs 36.7% women) and idiopathic etiologies (22.6% men vs 35.2% women) more often in women (P < .01 for all comparisons). Nonalcohol etiologies were equally divided among obstructive, genetic, and other causes. Compared with controls, patients with idiopathic CP were more likely to have ever smoked (58.6% vs 49.7%, P < .05) or have a history of chronic renal disease or failure (5.2% vs 1.2%, P < .01). In multivariate analyses, smoking (ever, current, and amount) was independently associated with idiopathic CP. CONCLUSIONS The frequency of alcohol-related CP at tertiary US referral centers is lower than expected. Idiopathic CP and nonalcohol etiologies represent a large subgroup, particularly among women. Smoking is an independent risk factor for idiopathic CP.

Type of pain, pain-associated complications, quality of life, disability and resource utilisation in chronic pancreatitis: a prospective cohort study

Objective To compare patients with chronic pancreatitis (CP) with constant pain patterns to patients with CP with intermittent pain patterns. Methods This was a prospective cohort study conducted at 20 tertiary medical centers in the USA comprising 540 subjects with CP. Patients with CP were asked to identify their pain from five pain patterns (A–E) defined by the temporal nature (intermittent or constant) and the severity of the pain (mild, moderate or severe). Pain pattern types were compared with respect to a variety of demographic, quality of life (QOL) and clinical parameters. Rates of disability were the primary outcome. Secondary outcomes included: use of pain medications, days lost from school or work, hospitalisations (preceding year and lifetime) and QOL as measured using the Short Form-12 (SF-12) questionnaire. Results Of the 540 CP patients, 414 patients (77%) self-identified with a particular pain pattern and were analysed. Patients with constant pain, regardless of severity, had higher rates of disability, hospitalisation and pain medication use than patients with intermittent pain. Patients with constant pain had lower QOL (by SF-12) compared with patients who had intermittent pain. Additionally, patients with constant pain were more likely to have alcohol as the aetiology for their pancreatitis. There was no association between the duration of the disease and the quality or severity of the pain. Conclusions This is the largest study ever conducted of pain in CP. These findings suggest that the temporal nature of pain is a more important determinant of health-related QOL and healthcare utilisation than pain severity. In contrast to previous studies, the pain associated with CP was not found to change in quality over time. These results have important implications for improving our understanding of the mechanisms underlying pain in CP and for the goals of future treatments and interventions.

Combined Bicarbonate Conductance-Impairing Variants in CFTR and SPINK1 Variants Are Associated With Chronic Pancreatitis in Patients Without Cystic Fibrosis

BACKGROUND & AIMS Idiopathic chronic pancreatitis (ICP) is a complex inflammatory disorder associated with multiple genetic and environmental factors. In individuals without cystic fibrosis (CF), variants of CFTR that inhibit bicarbonate conductance but maintain chloride conductance might selectively impair secretion of pancreatic juice, leading to trypsin activation and pancreatitis. We investigated whether sequence variants in the gene encoding the pancreatic secretory trypsin inhibitor SPINK1 further increase the risk of pancreatitis in these patients. METHODS We screened patients and controls for variants in SPINK1 associated with risk of chronic pancreatitis and in all 27 exons of CFTR. The final study group included 53 patients with sporadic ICP, 27 probands with familial ICP, 150 unrelated controls, 375 additional controls for limited genotyping. CFTR wild-type and p.R75Q were cloned and expressed in HEK293 cells, and relative conductances of HCO(3)(-) and Cl(-) were measured. RESULTS SPINK1 variants were identified in 36% of subjects and 3% of controls (odds ratio [OR], 18.1). One variant of CFTR not associated with CF, p.R75Q, was found in 16% of subjects and 5.3% of controls (OR, 3.4). Coinheritance of CFTR p.R75Q and SPINK1 variants occurred in 8.75% of patients and 0.38% of controls (OR, 25.1). Patch-clamp recordings of cells that expressed CFTR p.R75Q showed normal chloride currents but significantly reduced bicarbonate currents (P = .0001). CONCLUSIONS The CFTR variant p.R75Q causes a selective defect in bicarbonate conductance and increases risk of pancreatitis. Coinheritance of p.R75Q or CF causing CFTR variants with SPINK1 variants significantly increases the risk of ICP.

Mechanisms of CFTR Functional Variants That Impair Regulated Bicarbonate Permeation and Increase Risk for Pancreatitis but Not for Cystic Fibrosis

CFTR is a dynamically regulated anion channel. Intracellular WNK1-SPAK activation causes CFTR to change permeability and conductance characteristics from a chloride-preferring to bicarbonate-preferring channel through unknown mechanisms. Two severe CFTR mutations (CFTRsev) cause complete loss of CFTR function and result in cystic fibrosis (CF), a severe genetic disorder affecting sweat glands, nasal sinuses, lungs, pancreas, liver, intestines, and male reproductive system. We hypothesize that those CFTR mutations that disrupt the WNK1-SPAK activation mechanisms cause a selective, bicarbonate defect in channel function (CFTRBD) affecting organs that utilize CFTR for bicarbonate secretion (e.g. the pancreas, nasal sinus, vas deferens) but do not cause typical CF. To understand the structural and functional requirements of the CFTR bicarbonate-preferring channel, we (a) screened 984 well-phenotyped pancreatitis cases for candidate CFTRBD mutations from among 81 previously described CFTR variants; (b) conducted electrophysiology studies on clones of variants found in pancreatitis but not CF; (c) computationally constructed a new, complete structural model of CFTR for molecular dynamics simulation of wild-type and mutant variants; and (d) tested the newly defined CFTRBD variants for disease in non-pancreas organs utilizing CFTR for bicarbonate secretion. Nine variants (CFTR R74Q, R75Q, R117H, R170H, L967S, L997F, D1152H, S1235R, and D1270N) not associated with typical CF were associated with pancreatitis (OR 1.5, p = 0.002). Clones expressed in HEK 293T cells had normal chloride but not bicarbonate permeability and conductance with WNK1-SPAK activation. Molecular dynamics simulations suggest physical restriction of the CFTR channel and altered dynamic channel regulation. Comparing pancreatitis patients and controls, CFTRBD increased risk for rhinosinusitis (OR 2.3, p<0.005) and male infertility (OR 395, p<<0.0001). WNK1-SPAK pathway-activated increases in CFTR bicarbonate permeability are altered by CFTRBD variants through multiple mechanisms. CFTRBD variants are associated with clinically significant disorders of the pancreas, sinuses, and male reproductive system.

Fecal Pancreatic Elastase 1 Is Inaccurate in the Diagnosis of Chronic Pancreatitis

Many tests are available to assess pancreatic function. The ideal test would be simple and have adequate sensitivity in mild to moderate chronic pancreatitis (MCP) and severe CP (SCP). Fecal pancreatic elastase 1 (FPE1) assay (ScheBo Tech) has been proposed as a reliable test to evaluate pancreatic exocrine function, with sensitivities of up to 100% in diagnosing CP. Cutoff values (microgram/g stool) of < 100 have been suggested as SCP, 100-200 as MCP, and > 200 as normal. The tests ability to detect MCP distinguished by the absence of steatorrhea, and its specificity among various etiologies of malabsorption, has not been fully evaluated. The aim of this study was to evaluate this assay in subjects including patients with SCP with steatorrhea, patients with MCP with no steatorrhea, healthy controls, and diseased controls with nonpancreatic malabsorption. Thirty-six subjects [15 healthy controls, 7 malabsorption controls, and 14 subjects with CP (7 MCP, 7 SCP)] had FPE1 assays. One hundred fifty-four assays for FPE1 were run for analysis. The intraassay and interassay intraclass correlation coefficients were 0.93 and 0.90, respectively. All SCP had values of < 100 micrograms/g but more than half of the MCP subjects had FPE1 levels within the normal range. The subjects with nonpancreatic malabsorption had FPE1 values ranging from 55 to > 500 micrograms/g of stool. Although the assay detected SCP with steatorrhea, it did not consistently separate the MCP patients from normals. The majority of those with nonpancreatic malabsorption had false-positive values. These results may differ from previously described data because of the purposeful inclusion of MCP subjects, documented by the lack of steatorrhea, and the inclusion of disease controls with nonpancreatic malabsorption. Although PE1 concentrates in the stool and is not significantly degraded, subtle changes in this enzyme, as in MCP, do not seem to be detectable by this assay. This group continues to be the most difficult group to diagnose clinically.

Hereditary Pancreatitis in North America: The Pittsburgh-Midwest Multi-Center Pancreatic Study Group Study

Background: Hereditary pancreatitis (HP) was defined on a clinical basis alone until the first cationic trypsinogen gene (PRSS1) mutation was discovered through the initial phase of the current Pittsburgh Midwest Multi-Center Pancreatic Study Group (MMPSG) HP study in 1996, making genetic testing available. Aim: To evaluate the regional distribution of HP in the United States, and to compare the study’s gene mutation database with the pedigree databases to determine whether family history alone predicts the likelihood of detecting mutations in the cationic trypsinogen gene. Methods: Probands of families with HP, familial pancreatitis and idiopathic chronic pancreatitis were recruited through referrals from MMPSG collaborating centers, otehr physicians and self-referral of patients who had learned of the study through the World Wide Web (www.pancreas.org). Pedigrees were constructed, detailed questionnaires were completed and a blood sample was drawn for each proband and participating family members. The birthplace and current location of each patient was recorded, DNA was analyzed for known mutations and the pattern of phenotype inheritance was determined from analysis of each pedigree. Results: A total of 717 individuals were ascertained; 368 (51%) had clinical pancreatitis confirmed and the rest were primarily unaffected family members used for linkage studies. Forty-six clinically unaffected individuals were silent mutation carriers (11% of mutation-positive individuals). HP was most common in Minnesota, New York and the central mid-Atlantic states plus Kentucky and Ohio. One hundred and fifteen of 150 kindreds fulfilled the strict definition of an HP family, and 60 (52%) had PRSS1 mutations. Of the families with a detected mutation, 11% did not fulfill the clinical definition of an HP kindred. Conclusions: The distribution of HP within the United States shows major regional differences. The etiology of HP can be identified in a small majority of HP families through genetic testing. However, family history alone is not a good predictor of finding a mutation in the cationic trypsinogen (PRSS1) gene.

Expression and penetrance of the hereditary pancreatitis phenotype in monozygotic twins

BACKGROUND Hereditary pancreatitis (HP) is a rare autosomal dominant disorder with variable expression and an overall lifetime penetrance of 80%. We hypothesised that (1) monozygotic twins within similar environments would develop the typical signs of HP at a similar age, and (2) if penetrance were due to modifier genes or environment, all twin pairs would be concordant for expression of HP. AIM Identify monozygotic twins with HP and determine the penetrance, concordance, and age of onset of symptoms. METHODS Twins from HP kindreds were identified from the Midwest Multicenter Pancreatic Study group database, referrals, and literature searches. Each twin set was assessed for phenotypic expression, concordance, and difference in age of phenotypic onset of pancreatitis. The difference in onset of symptoms for symptomatic affected non-twin sibling pairs as well as non-twin pairs that were mutation, sex, and age matched were calculated as two comparison groups. RESULTS Seven of 11 monozygotic pairs identified were suitable for evaluation and four were concordant for pancreatitis. Forty eight affected sibling pairs and 33 pairs of mutation, sex, and age matched (cationic trypsinogen R122H (30 pairs) and N29I (three pairs)) subjects were identified for comparison groups. The median (quartiles Q1, Q3) difference in the age of phenotypic onset in the concordant twins was 1 (0, 2.4) years, 2 (1, 6) for the affected siblings, and 7 (2, 15) years in the comparison control group. Three of the seven sets of twins (43%) were discordant for phenotypic expression of pancreatitis. The overall penetrance in the seven pairs of monozygotic twins was 78.6%. CONCLUSIONS Genetic and/or environmental factors contribute to expression and age of onset of HP. Nuclear genes or general environmental factors alone cannot explain the 80% penetrance. Determining the mechanism of non-penetrance may help in developing a strategy to prevent the phenotypic expression of pancreatitis in individuals with an underlying genetic predisposition.

Physical and mental quality of life in chronic pancreatitis: a case-control study from the North American Pancreatitis Study 2 cohort.

Objectives The objective of this study was to define the quality of life (QOL) in patients with chronic pancreatitis (CP). Methods We studied 443 well-phenotyped CP subjects and 611 control subjects prospectively enrolled from 20 US centers between 2000 and 2006 in the North American Pancreatitis Study 2. Responses to the SF-12 questionnaire were used to calculate the mental (MCS) and physical component summary scores (PCS) with norm-based scoring (normal ≥50). Quality of life in CP subjects was compared with control subjects after controlling for demographic factors, drinking history, smoking, and medical conditions. Quality of life in CP was also compared with known scores for several chronic conditions. Results Both PCS (38 [SD, 11.5] vs 52 [SD, 9.4]) and MCS (44 [SD, 11.5] vs 51 [SD, 9.2]) were significantly lower in CP compared with control subjects (P < 0.001). On multivariable analyses, compared with control subjects, a profound decrease in physical QOL (PCS 12.02 points lower) and a clinically significant decrease in mental QOL (MCS 4.24 points lower) was seen due to CP. Quality of life in CP was similar to (heart, kidney, liver, lung disease) or worse than (nonskin cancers, diabetes mellitus, hypertension, rheumatoid arthritis) other chronic conditions. Conclusions The impact of CP on QOL appears substantial. The QOL in CP subjects appears to be worse or similar to the QOL of many other chronic conditions.

Smoking is underrecognized as a risk factor for chronic pancreatitis

Background/Aims: Smoking is an established risk factor for chronic pancreatitis (CP). We sought to identify how often and in which CP patients physicians consider smoking to be a risk factor. Methods: We analyzed data on CP patients and controls prospectively enrolled from 19 US centers in the North American Pancreatitis Study-2. We noted each subject’s self-reported smoking status and quantified the amount and duration of smoking. We noted whether the enrolling physician (gastroenterologist with specific interest in pancreatology) classified alcohol as the etiology for CP and selected smoking as a risk factor. Results: Among 382/535 (71.4%) CP patients who were self-reported ever smokers, physicians cited smoking as a risk factor in only 173/382 (45.3%). Physicians cited smoking as a risk factor more often among current smokers, when classifying alcohol as CP etiology, and with higher amount and duration of smoking. We observed a wide variability in physician decision to cite smoking as a risk factor. Multivariable regression analysis however confirmed that the association of CP with smoking was independent of physician decision to cite smoking as a risk factor. Conclusions: Physicians often underrecognize smoking as a CP risk factor. Efforts are needed to raise awareness of the association between smoking and CP.

Use and perceived effectiveness of non-analgesic medical therapies for chronic pancreatitis in the United States

Aliment Pharmacol Ther 2011; 33: 149–159