Hospital discharge data for Guillain-Barré syndrome and influenza A (H1N1) vaccine adverse events

Readmissions After Guillain-Barre Syndrome: Nationally Representative Data

OBJECTIVES

We aimed to obtain nationally representative data on hospital readmission rates after Guillain-Barre syndrome (GBS).

METHODS

International Classification of Disease, Ninth Revision codes from the 2013 National Readmissions Database identified adult GBS admissions, comorbidities, and readmission diagnoses. Logistic regression estimated odds ratios (ORs) for readmission.

RESULTS

Of 2109 GBS admissions identified, 20.8% were readmitted within 1 year and 12.2% within 30 days. Age did not predict readmission. Plasmapheresis use showed a nonsignificant trend toward readmission versus intravenous immunoglobulin use [OR 1.43, 95% confidence interval (CI) 1.00-2.051, P = 0.050]. Respiratory failure (OR 1.70, 95% CI 1.23-2.35, P = 0.0014), heart failure (OR 2.14, 95% CI 1.25-3.66, P = 0.0057), and renal failure (OR 2.00, 95% CI 1.20-3.32, P = 0.0078) predicted readmission. Top readmission diagnoses included GBS or chronic inflammatory demyelinating polyneuropathy (42.0%) and sepsis (3.5%).

CONCLUSIONS

One-fifth of GBS patients were readmitted within 1 year. Comorbid illnesses and respiratory complications increased a readmission risk but age did not.

Incidence of Campylobacter-Associated Guillain-Barré Syndrome Estimated from Health Insurance Data

Guillain-Barré syndrome (GBS) is sometimes preceded by Campylobacter infection. We estimated the cumulative incidence of Campylobacter-associated GBS in the United States using a retrospective cohort design. We identified a cohort of patients with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code of "intestinal infection due to Campylobacter" (008.43) using MarketScan Research Databases for 2004-2013. Campylobacter patients with an encounter for "acute infective polyneuritis" (AIP; ICD-9-CM 357.0) were identified. Patients with an inpatient encounter having AIP as the principal diagnosis were considered probable GBS cases. Patients with probable GBS ≤8 weeks after the Campylobacter encounter were considered probable Campylobacter-associated GBS cases. For comparison, we repeated this analysis for patients with "other Salmonella infections" (ICD-9-CM: 003). Among 9315 Campylobacter patients, 16 met the case definition for probable GBS. Two were hospitalized with probable GBS ≤8 weeks after the encounter listing a Campylobacter diagnosis (9 and 54 days) and were considered probable cases of Campylobacter-associated GBS; this results in an estimated cumulative incidence of 21.5 per 100,000 Campylobacter patients (95% confidence interval [CI]: 3.7-86.6), or 5% of all estimated GBS cases. The remaining 14 patients were diagnosed with probable GBS on the same encounter (n = 12) or 1-3 days (n = 2), before the encounter listing the Campylobacter diagnosis. Including these cases increased the cumulative incidence to 172 per 100,000 Campylobacter cases (95% CI: 101.7-285.5), 41% of estimated GBS cases. This study, using a method not previously applied to United States data, supports other data that Campylobacter is an important contributor to GBS, accounting for at least 5% and possibly as many as 41% of all GBS cases. These data can be used to inform estimates of the burden of Campylobacter infections, including economic cost.

Hyponatremia in Guillain-Barré Syndrome

OBJECTIVES

To evaluate incidence, risk factors, and in-hospital outcomes associated with hyponatremia in patients hospitalized for Guillain-Barré Syndrome (GBS).

METHODS

We identified adult patients with GBS in the Nationwide Inpatient Sample (2002-2011). Univariate and multivariable analyses were used.

RESULTS

Among 54,778 patients hospitalized for GBS, the incidence of hyponatremia was 11.8% (compared with 4.0% in non-GBS patients) and increased from 6.9% in 2002 to 13.5% in 2011 (P < 0.0001). Risk factors associated with hyponatremia in multivariable analysis included advanced age, deficiency anemia, alcohol abuse, hypertension, and intravenous immunoglobulin (all P < 0.0001). Hyponatremia was associated with prolonged length of stay (16.07 vs. 10.41, days), increased costs (54,001 vs. 34,125, $USD), and mortality (20.5% vs. 11.6%) (all P < 0.0001). In multivariable analysis, hyponatremia was independently associated with adverse discharge disposition (odds ratio: 2.07, 95% confidence interval, 1.91-2.25, P < 0.0001).

CONCLUSIONS

Hyponatremia is prevalent in GBS and is detrimental to patient-centered outcomes and health care costs. Sodium levels should be carefully monitored in high-risk patients.

Relationship between Guillain-Barré syndrome, influenza-related hospitalizations, and influenza vaccine coverage

Some studies reported an increased risk of Guillain-Barré syndrome (GBS) within six weeks of influenza vaccination. It has also been suggested that this finding could have been confounded by influenza illnesses. We explored the complex relationship between influenza illness, influenza vaccination, and GBS, from an ecologic perspective using nationally representative data. We also studied seasonal patterns for GBS hospitalizations. Monthly hospitalization data (2000-2009) for GBS, and pneumonia and influenza (P&I) in the Nationwide Inpatient Sample were included. Seasonal influenza vaccination coverage for 2004-2005 through the 2008-2009 influenza seasons (August-May) was estimated from the National Health Interview Survey data. GBS seasonality was determined using Poisson regression. GBS and P&I temporal clusters were identified using scan statistics. The association between P&I and GBS hospitalizations in the same month (concurrent) or in the following month (lagged) were determined using negative binomial regression. Vaccine coverage increased over the years (from 19.7% during 2004-2005 to 35.5% during 2008-2009 season) but GBS hospitalization did not follow a similar pattern. Overall, a significant correlation between monthly P&I and GBS hospitalizations was observed (Spearman's correlation coefficient=0.7016, p<0.0001). A significant (p=0.001) cluster of P&I hospitalizations during December 2004-March 2005 overlapped a significant (p=0.001) cluster of GBS hospitalizations during January 2005-February 2005. After accounting for effects of monthly vaccine coverage and age, P&I hospitalization was significantly associated (p<0.0001) with GBS hospitalization in the concurrent month but not with GBS hospitalization in the following month. Monthly vaccine coverage was not associated with GBS hospitalization in adjusted models (both concurrent and lagged). GBS hospitalizations demonstrated a seasonal pattern with winter months having higher rates compared to the month of June. P&I hospitalization rates were significantly correlated with hospitalization rates for GBS. Vaccine coverage did not significantly affect the rates of GBS hospitalization at the population level.

Guillain-Barré syndrome and H1N1 (2009) pandemic influenza vaccination using an AS03 adjuvanted vaccine in the United Kingdom: self-controlled case series

In 1976 a swine influenza vaccine was associated with an increased risk of Guillain-Barré syndrome (GBS). Although subsequent studies did not find an increased risk of GBS following seasonal influenza vaccine, there was concern that the monovalent H1N1 vaccines developed against the swine influenza pandemic of 2009 might increase the risk of GBS. In the UK a split-virion AS03 oil-in-water adjuvanted vaccine (Pandemrix™) was predominantly used. To determine whether the risk of GBS increased after Pandemrix administration, we sought GBS cases during the period of vaccine use from neurologists and a patient support group, and following the vaccination period from hospital episode statistics (HES) in England. We obtained cases' vaccination histories and illness onset dates from general practitioners. We determined the relative incidence of GBS in the 6 weeks after vaccination using the self-controlled case series method on the cases identified in HES. We included 327 GBS cases, of whom 37 received pandemic vaccine in the study period, nine of whom developed GBS within 6 weeks of vaccination (relative incidence 1.05 [95% confidence interval (CI) 0.37 to 2.24]). We found no evidence of an increased risk of GBS in the 6 weeks following pandemic influenza vaccination.