Journal of Medical Sciences

: 2020  |  Volume : 40  |  Issue : 1  |  Page : 8--16

Increased risk of acute pancreatitis in patients with sjögren syndrome: A nationwide population-based cohort study

Ming-Tsung Chen1, Chung-Kuang Yao2, Chi-Hsiang Chung3, Chih-Hao Shen1, Sheng-Huei Wang1, Chih-Hsin Wang4, Wu-Chien Chien5, Chung-Kan Peng1,  
1 Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
2 Division of Pulmonary and Critical Care, Department of Internal Medicine, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan
3 Department of Medical Research, Tri-Service General Hospital, School of Public Health, National Defense Medical Center, Taiwanese Injury Prevention and Safety Promotion Association, Taipei, Taiwan
4 Division of Plastic and Reconstructive Surgery, Department of Surgery, Tri-Service General Hospital, Taipei, Taiwan
5 Department of Medical Research, Tri-Service General Hospital, School of Public Health, National Defense Medical Center, Taipei, Taiwan

Correspondence Address:
Dr. Chung-Kan Peng
No. 325, Section 2, Chenggong Road, Neihu District, Taipei
Dr. Wu-Chien Chien
No. 325, Section 2, Chenggong Road, Neihu District, Taipei


Background: Sjögren's syndrome (SS) is a chronic autoimmune disease with lymphocytic exocrine gland infiltration causing dry mouth and eyes. The disease can develop alone (primary SS, PSS) or with other autoimmune diseases (secondary SS, SSS). PSS has been suggested to increase the acute pancreatitis risk. However, whether all patients with SS share this higher risk remains uncertain. This nationwide population-based cohort study aimed to detect associations between SS and acute pancreatitis. Methods: We identified 11,922 individuals with SS cohort and 47,688 individuals without SS (non-SS cohort) between 2000 and 2010 from the Taiwan National Health Insurance database. We matched the individuals between the SS and non-SS cohorts according to age, gender, and index year at a 1:4 ratio. We used a Cox multivariable proportional-hazards model to determine the effects of SS on the acute pancreatitis risk. Results: The SS cohort had a higher acute pancreatitis risk than the non-SS cohort after covariate adjustments (adjusted hazard ratio [HR], 3.374; 95% confidence interval [CI], 2.869–3.969). Patients with PSS exhibited a 2.872-fold risk (95% CI, 2.611–3.901) and patients with SSS a 4.121-fold risk (95% CI, 3.752–5.124) for acute pancreatitis. Our subgroup analyses revealed that patients with SS and systemic lupus erythematosus (adjusted HR, 3.85; 95% CI, 3.259–4.999), rheumatoid arthritis (adjusted HR, 4.298; 95% CI, 3.862–5.286), systemic sclerosis (adjusted HR, 2.765; 95% CI, 2.26–3.68), or polymyositis (adjusted HR, 2.641; 95% CI,1.847–3.101) and dermatomyositis (adjusted HR, 3.77; 95% CI, 2.894–4.502) had higher acute pancreatitis risk. Conclusions: Patients with SS presented increased acute pancreatitis risks than patients without SS, and patients with SSS had higher acute pancreatitis risks than patients with PSS. Physicians should be aware of this increased risk in patients with SS.

How to cite this article:
Chen MT, Yao CK, Chung CH, Shen CH, Wang SH, Wang CH, Chien WC, Peng CK. Increased risk of acute pancreatitis in patients with sjögren syndrome: A nationwide population-based cohort study.J Med Sci 2020;40:8-16

How to cite this URL:
Chen MT, Yao CK, Chung CH, Shen CH, Wang SH, Wang CH, Chien WC, Peng CK. Increased risk of acute pancreatitis in patients with sjögren syndrome: A nationwide population-based cohort study. J Med Sci [serial online] 2020 [cited 2020 Feb 25 ];40:8-16
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Full Text


Sjögren's syndrome (SS) is a systemic slowly progressing autoimmune disease commonly affecting lacrimal and salivary glands. Approximately 30%–40% of the patients with SS have systemic manifestations involving the lungs, skin, central nerve system, kidneys, or other organs. The pathogenesis of SS includes a genetic predisposition, innate and adaptive immunity abnormalities, and hormonal and environmental factors.[1],[2],[3] The American-European Consensus Classification Criteria are available to diagnose SS based on symptoms, signs, histopathology from salivary gland biopsy, and autoantibodies such as Anti-SSA (Ro) or Anti-SSB (La).[4]

SS is most common in middle-aged women but can occur in men and at any age. SS incidence and prevalence rates vary widely around the world.[5] The disease can present alone (primary SS, PSS) or with other autoimmune diseases (secondary SS, SSS). About 30% of patients with autoimmune rheumatic disease have SSS.[6] SSS can coexist with systemic lupus erythematosus (SLE) (15%–36%), rheumatoid arthritis (RA) (20%–32%), systemic sclerosis (SSc) (11%–24%), or polymyositis (9%–18%).[7] Some studies have focused on differences between PSS and SSS, and patients with PSS have predominantly B lymphocyte infiltration in the lip biopsy and a higher frequency of parotid enlargement, oral symptoms, and titers of anti-Ro/La autoantibodies than patients with SSS.[8]

The pancreas exerts both exocrine and endocrine functions, and secreted pancreatic juice contains bicarbonate and digestive enzymes that assist digestion and the absorption of nutrients in the small intestine. Acute pancreatitis is an acute inflammatory process of the pancreas and is also a public health issue associated with severe morbidity and mortality. The global incidence of acute pancreatitis is 33.74/100,000 person-years, and the mortality is 1.16/100,000 person-years.[9] Many factors can induce acute pancreatitis, gallstone and alcohol abuse being the most common (about 70%). The frequency of acute pancreatitis associated with another autoimmune disease is <1%.[10]

SS is an autoimmune disease involving exocrine glands. Chronic pancreatitis has been found in association with other autoimmune diseases such as SS, primary biliary cirrhosis, and sclerosing cholangitis.[11],[12],[13] A study on the association between PSS and acute pancreatitis showed that PSS may increase the acute pancreatitis risk, but the study population excluded individuals with coexisting autoimmune diseases. 14 Since SS may concur with other autoimmune diseases, the association between SS and acute pancreatitis remains unclear. We conducted a nationwide population-based cohort study to assess whether SS increases the acute pancreatitis risk.


Data source

We used data from the National Health Insurance Research Database (NHIRD). The NHIRD contains health insurance claim data from the Taiwan NHI program. The Taiwanese government established the NHI in 1995 as a single-payer, compulsory program for all 23 million Taiwanese citizens. The database from the NHIRD contains comprehensive information including a beneficiary registry, demographic data, diagnostic codes, and prescription codes. The diagnostic codes are recorded according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). To protect patient privacy, the NHIRD removes identifying information and assigns an anonymous number before releasing patient records for research. We used the Longitudinal Health Insurance Database (LHID), a subset of the NHIRD, for establishing our study. The Institutional Review Board of Tri-Service General Hospital approved this study.

Sampled patients

We conducted a nationwide population-based cohort study to investigate the association between SS and acute pancreatitis risk. The LHID included patients older than 20 years and diagnosed as having SS (ICD-9-CM code 710.2) between 2000 and 2010 [Figure 1]. Physicians confirmed the diagnoses according to the American-European Consensus Group diagnostic criteria.[4] We excluded any patients with a history of acute pancreatitis (ICD-9-CM code 577.0), chronic pancreatitis (ICD-9-CM code 577.1), or a malignant neoplasm in the pancreas (ICD-9-CM code 157) before the index date, patients younger than 20 years, and those with incomplete medical information. We randomly chose the SS and non-SS cohorts from the LHID and matched them by frequency according to their age, gender, and index year at a 1:4 ratio. The exclusion criteria for the non-SS cohort were the same as those for the SS cohort. We also divided patients with SS into those with PSS and those with SSS for subgroup analyzes. We defined SSS as syndrome including SS accompanying another rheumatic disease such as SLE (ICD-9-CM code 710.0), RA (ICD-9-CM code 714.0), SSc (ICD-9-CM code 710.1), polymyositis (ICD-9-CM code 710.4), or dermatomyositis ((ICD-9-CM code 710.3).{Figure 1}

Outcome and comorbidities

All the patients were followed up from the index date until the time of a diagnosis of acute pancreatitis, withdrawal from the NHI program, or December 31, 2010. Baseline comorbidities, such as diabetes mellitus (DM) (ICD-9-CM code 250), hypertriglyceridemia (ICD-9-CM code 272.1), biliary stones (ICD-9-CM code 574), alcohol-related diseases (ARD) (ICD-9-CM codes 291, 303, 305.00–305.03, 790.3, and V11.3), hepatitis C (ICD-9-CM codes 070.41, 070.44, 070.51, 070.54, and V02.62), hepatitis B (ICD-9-CM codes 070.20, 070.22, 070.30, 070.32, and V02.61), cardiovascular disease (CVD) (ICD-9-CM codes 410–414, 428, 430–438, and 440–448), chronic kidney disease (CKD) (ICD-9-CM codes 585–586 and 588.8–588.9), and chronic obstructive pulmonary disease (COPD) (ICD-9-CM codes 491–493 and 496) were also included in our analyses.

Statistical analysis

We compared the distributions of categorical characteristics and baseline comorbidities between patients with or without SS using the Chi-square test. In addition, we compared continuous variables between the cohorts using Student's t-tests. We plotted the cumulative incidence of acute pancreatitis for each cohort based on the Kaplan–Meier method and used the log-rank test to analyze differences between the survival curves. The univariate and multivariate Cox proportion hazards regression models were used to analyze the incidence densities (per 10[5] person-years) of acute pancreatitis in each cohort, and we obtained hazard ratios (HRs) categorized by gender, age, and comorbidities such as DM, hypertriglyceridemia, biliary stones, ARD, hepatitis C, hepatitis B, CVD, CKD, and COPD. We performed all analyzes using the SAS 9.4 software (SPSS, Chicago, IL, USA) and considered 2-side tests' P 0.05 as statistically significant.


We included 11,922 patients in the SS cohort and 47,688 patients in the comparison (non-SS) cohort. The age and gender distributions between both cohorts were similar. The patients were predominantly women (81.26%), and most ages ranged between 45 and 69 years (51.35%). Patients with SS had a higher prevalence of hepatitis C and hepatitis B and a lower prevalence of DM, hypertriglyceridemia, biliary stones, ARD, CVD, and COPD than patients without SS [Table 1]. The mean follow-up years for SS and non-SS cohorts were 6.89 ert. 51 and 7.12 ert. 67 years, respectively.{Table 1}

Patients with SS had a higher acute pancreatitis risk than patients without SS (adjusted HR, 3.374; 95% confidence interval [CI], 2.869–3.969; P < 0.001) in the multivariate Cox model [Table 2]. The acute pancreatitis risk was higher in men, in patients aged from 45 to 69 years, and in those with DM, hypertriglyceridemia, biliary stones, ARD, or CKD. The cumulative incidence for acute pancreatitis in subsequent years was higher in the SS cohort than in the comparison cohort (log-rank test, P < 0.001) [Figure 2].{Table 2}{Figure 2}

[Table 3] shows the stratified analysis based on gender, age, and comorbidities. The gender-specific relative acute pancreatitis risk in patients with SS was higher than that in patients without SS regardless of gender (adjusted HR, 3.971; 95% CI, 3.305–4.722; adjusted HR, 2.013; 95% CI, 1.410–2.873). The age-specific relative acute pancreatitis risk in patients with SS was higher than in those without SS regardless of the age group. The adjusted HR for acute pancreatitis was higher in patients with SS than in those without it, regardless of the presence of DM (adjusted HR, 3.179; 95% CI, 2.094–4.826), biliary stones (adjusted HR, 3.781; 95% CI, 3.164–4.525), HCV (adjusted HR, 6.545; 95% CI, 2.064–20.750), HBV (adjusted HR, 10.934; 95% CI, 2.044–58.491), CVD (adjusted HR, 3.377; 95% CI, 1.966–5.662), CKD (adjusted HR, 2.499; 95% CI, 1.131–5.523), or COPD (adjusted HR, 4.740; 95% CI, 2.146–10.471).{Table 3}

In [Table 4], the subgroup analysis revealed that patients with PSS or SSS both had significantly increased acute pancreatitis risks than patients without SS (adjusted HR, 2.872; 95% CI, 2.611–3.901; and adjusted HR, 4.121; 95% CI, 3.752–5.124, respectively). Besides, patients with SS and SLE, RA, SSc, or polymyositis and dermatomyositis had higher acute pancreatitis risks (adjusted HR, 3.85; 95% CI, 3.259–4.999; adjusted HR, 4.298; 95% CI, 3.862–5.286; adjusted HR, 2.765; 95% CI, 2.26–3.68; adjusted HR, 2.641; 95% CI, 1.847–3.101; and adjusted HR, 3.77; 95% CI, 2.894–4.502) than the patients in the non-SS cohort. Patient with PSS and SSS exhibited a significantly increased cumulative acute pancreatitis risk in subsequent years than the patients without SS (log-rank test, P < 0.001) [Figure 3].{Table 4}{Figure 3}


We conducted a nationwide population-based cohort study to investigate the acute pancreatitis risk in patients with SS after subgroup analyses. After adjusting for gender, age, and comorbidities, the multivariate Cox model showed that patients with SS had a 3.374-fold higher acute pancreatitis risk than those without SS. This study also showed that patients with SSS (including SLE, RA, SSc, polymyositis, and dermatomyositis) had higher acute pancreatitis risks than patients in the non-SS cohort (adjusted HR, 4.121; 95% CI, 3.752–5.124).

We observed that patients with SS had a significantly higher acute pancreatitis incidence than the comparison cohort, regardless of gender, age, and comorbidities such as DM, biliary stones, HCV, HBV, CVD, CKD, and COPD [Table 3]. Like other studies, ours indicated that middle-aged men, the presence of DM, hypertriglyceridemia, biliary stones, ARD, or CKD are independent risk factors for acute pancreatitis [Table 2].[10],[15],[16] These findings strengthen the finding of SS being an independent factor for acute pancreatitis.

Our study showed a 2.872-fold higher acute pancreatitis risk in patients with PSS and a 4.121-fold higher risk in patients with SSS than the risk in the non-SS cohort. The exact mechanism of PSS-induced acute pancreatitis remains unknown. The activation of the innate immune system and production of interferons (IFNs) could represent the first PSS pathogenesis stages. Dendritic cell-secreted interleukin (IL)-12 leads to the activation of natural killer cells and type-1 T­helper cells that increase IFN-γ production and mediate tissue damage. Besides, IFN-α and IFN-γ enhance B­cell­activating factor (BAFF) secretion, creating a bridge between innate immunity and autoimmune B­cell activation in patients with PSS.[17],[18] One study showed serum BAFF levels increasing significantly in patients with acute pancreatitis due to an acute phase reaction, and the levels reflected the disease severity.[19] The immune cells and cytokine interaction may play a crucial role in PSS-induced acute pancreatitis.

Our study showed patients with SS and other autoimmune diseases had higher acute pancreatitis risks than patients with PSS. Another study had shown that patients with overlapping SS and RA had a higher prevalence of arthritis, interstitial lung disease, and anemia, with elevated erythrocyte sedimentation rate, and high C-reactive protein levels than patients with PSS.[20] A possible mechanism by which RA increases the acute pancreatitis risk may involve a vasculitis that causes pancreatic ischemia.[21],[22] On the other hand, patients with SLE and SS display a higher frequency of Raynaud's phenomenon, arthritis, central nervous system involvement, serositis, and perivascular infiltrates in the salivary glands than patients with PSS.[23] In a Chinese population study, 27 of 4053 patients with SLE had acute pancreatitis with a high mortality rate (37.04%) due to severe SLE activity and multiple organ involvement.[24] The mechanism of SLE-related acute pancreatitis is multifactorial and includes vascular damage, drug toxicity, autoantibody reactions, or abnormal cellular immune responses.[25],[26] Few case reports have presented juvenile dermatomyositis with pancreatitis; in those cases, vasculitis was the possible cause for the SLE-related pancreatitis.[27] However, no study has examined the association between acute pancreatitis and either scleroderma or polymyositis. We hypothesize that the presence of multiple autoimmune diseases may worsen the inflammation process and vasculitis, thereby increasing the acute pancreatitis risk in patients with SS.

Autoimmune pancreatitis (AIP) was first described by Yoshida et al. in 1995,[28] and the term was adopted for pancreatic disease of an autoimmune origin. The diagnostic AIP criteria proposed by the Mayo Clinic (the “HISORt” criteria) include 5 items: histology, imaging, serum immunoglobulin G4 (IgG4) level, other organ involvement, and response to therapy.[29] AIP is classified into two subtypes. Type 1 AIP is a systemic disease affecting the pancreas, salivary glands, and kidneys, while type 2 AIP affects only the pancreas.[10],[30],[31] A serum IgG4 concentration ≥2 times the upper normal limit is highly suggestive of AIP.[32] Some studies have shown raised IgG4 serum levels and IgG4-positive plasma cell infiltration in labial salivary glands of patients with SS.[33],[34] Because we could not record the IgG4 level in this retrospective cohort study, the role of IgG4 in AIP and SS needs to be further studied.

We are aware of the limitations of our study. First, the NHIRD lacks information on patient behaviors, physical examinations, and crucial acute pancreatitis risk factors, such as smoking, obesity or BMI, dietary habits, and alcohol consumption. Second, relevant clinical variables including laboratory data, imaging results, and lip biopsy results were unavailable in the database. Third, due to the retrospective nature of our cohort study, bias from unknown confounders may have affected our results, and a well-designed randomized prospective control study is still necessary to help establish a causal relationship.


This study demonstrated that patients with SS exhibited a 3.374-fold higher acute pancreatitis risk than individuals in the general population. Both PSS and SSS increased the acute pancreatitis risk. Physicians should be aware of the possibility of acute pancreatitis when caring for patients with SS, particularly also having other autoimmune diseases.


This study was based in part using data from the NHIRD, which is managed and provided by the National Health Research Institutes, Taiwan. The conclusions and interpretations in this article do not represent the views of the Department of Health, the Bureau of the NHI, or the National Health Research Institutes. The study is approved by Institutional Review Board of Tri-Service General Hospital. The approval number is 2-105-05-082.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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