Skip to main content
Publications
Gini R, Pajouheshnia R , Gutierrez L , Swertz MA, Hyde E, Sturkenboom M, Arana A , Franzoni C , Ehrenstein V, Roberto G, Gil M, Macia MA, Schafer W, Haug U, Thurin NH, Lassalle R, Droz-Perroteau C, Zaccagnino S, Busto MP, Middelkoop B, Gembrt K, Sanchez-Saez F, Rodriguez-Bernal C, Sanfelix-Gimeno G, Hurtado I, Barreiro-de Acosta M, Poblador-Plou B, Carmona-Pirez J, Gimeno-Miguel A, Prados-Torres A, Schultze A, Jansen E, Herings R, Kuiper J, Locatelli I, Jazbar J, Zerovnik S, Kos M, Smit S, Lind S, Metspalu A, Simou S, Hedenmalm K, Cochino A, Alcini P, Kurz X, Perez-Gutthann S . Commentary - Metadata for data dIscoverability aNd study rEplicability in obseRVAtional studies: lessons learnt from the MINERVA project in Europe . Pharmacoepidemiol Drug Saf. 2024 Aug;33(8):e5884. doi: 10.1002/pds.5884
Pajouheshnia R , Gini R, Gutierrez L , Swertz MA, Hyde E, Sturkenboom M, Arana A , Franzoni C , Ehrenstein V, Roberto G, Gil M, Macia MA, Schafer W, Haug U, Thurin NH, Lassalle R, Droz-Perroteau C, Zaccagnino S, Busto MP, Middelkoop B, Gembert K, Sanchez-Saez F, Rodriguez-Bernal C, Sanfelix-Gimeno G, Hurtado I, Barreiro-de Acosta M, Poblador-Plou B, Carmona-Pirez J, Gimeno-Miguel A, Prados-Torres A, Schultze A, Jansen E, Herings R, Kuiper J, Locatelli I, Jazbar J, Zerovnik S, Kos M, Smit S, Lind S, Metspalu A, Simou S, Hedenmalm K, Cochino A, Alcini P, Kurz X, Perez-Gutthann S . Metadata for data dIscoverability aNd study rEplicability in obseRVAtional studies (MINERVA): development and pilot of a metadata list and catalogue in Europe . Pharmacoepidemiol Drug Saf. 2024 Aug;33(8):e5871. doi: 10.1002/pds.5871
de Vogel S, Seeger JD, Arana A , Margulis AV , McQuay LJ, Perez-Gutthann S , Hallas J, Kristiansen NS, Linder M, Odsbu I, Suehs B, Xu Y, Uribe C, Appenteng K, Robinson NJ. Lessons learned from a multi-data source research collaboration: the mirabegron post-authorization safety study program . Pharmacoepidemiol Drug Saf. 2024 May;33(5):e5799. doi: 10.1002/pds.5799
Tormos A , Thomsen RW, Tave AK, Madsen M, Beachler DC, Martinez D , Garcia Esteban R , Plana E , Farsani SF, Perez-Gutthann S , Pladevall-Vila M , Rebordosa C . Post-authorisation safety study (PASS) assessing the risk of liver, renal, genitourinary, and diabetic ketoacidosis outcomes among users of empagliflozin versus DPP-4 inhibitors in patients with type 2 diabetes mellitus (T2D) . Poster presented at the 39th ICPE Annual Conference; August 27, 2023. Halifax, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2023 Oct 12; 32(S1):585. doi: 10.1002/pds.5687
Wang SV, Pottegard A, Crown W, Arlett P, Ashcroft DM, Benchimol EI, Berger ML, Crane G, Goettsch W, Hua W, Kabadi S, Kern DM, Kurz X, Langan S, Nonaka T, Orsini L, Perez-Gutthann S , Pinheiro S, Pratt N, Schneeweiss S, Toussi M, Williams RJ. HARmonized protocol template to enhance reproducibility of hypothesis evaluating real-world evidence studies on treatment effects: a good practices report of a joint ISPE/ISPOR task force . Pharmacoepidemiol Drug Saf. 2023 Jan;32(1):44-55. doi: 10.1002/pds.5507
Gini R, Paoletti O, Pajouheshnia R , Souverein PC, Thurin NH, Ehrenstein V, Barreiro-de Acosta M, Sturkenboom M, Gutierrez L , Perez-Gutthann S . Study scripts supporting multiple common data models . Poster presented at the 2022 ICPE Conference; August 28, 2022. Copenhagen, Denmark. [abstract] Pharmacoepidemiol Drug Saf. 2022 Sep 23; 31(S2):550. doi: 10.1002/pds.5518Pharmacoepidemiol Drug Saf.2022;31(Suppl. 2):3–628.wileyonlinelibrary.com/journal/pds© 2022 John Wiley & Sons Ltd.3
Pajouheshnia R , Gini R, Hyde E, Swertz MA, Sturkenboom M, Margulis AV , Franzoni C , Arana A , Ehrenstein V, Gembert K, Jansen E, Herings RMC, Thurin NH, Locatelli I, Jazbar J, Zerovnik S, Kos M, Smit S, Lind S, Metspalu A, Zaccagnino S, Busto MP, Middelkoop B, Barreiro-de Acosta M, Saez FS, Rodriguez-Bernal C, Sanfelix-Gimeno G, Poblador-Plou B, Carmona-Pirez J, Gimeno-Miguel A, Gil M, Schafer W, Haug U, Simou S, Hedenmalm K, Cochino A, Alcini P, Kurz X, Gutierrez L , Perez-Gutthann S . MINERVA: Metadata for data dIscoverability aNd study rEplicability in obseRVAtional studies . Poster presented at the 2022 ICPE Conference; August 28, 2022. Copenhagen, Denmark. [abstract] Pharmacoepidemiol Drug Saf. 2022 Sep 23; 31(S2):564. doi: 10:1002/pds.5518
Fortuny J , von Gersdorff G, Lassalle R, Linder M, Overbeek J, Reinold J, Toft G, Timmer A, Dress J, Blin P, Droz-Perroteau C, Ehrenstein V, Franzoni C , Herings R, Kollhorst B, Moore N, Odsbu I, Perez-Gutthann S , Schink T, Rascher K, Rasouliyan L, Rothman KJ , Saigi-Morgui N , Schaller M, Smits E, Forstner M, Intravenous Iron Consortium, Benichou J, Bircher AJ, Garbe E, Rampton DS, Gutierrez L . Use of intravenous iron and risk of anaphylaxis: a multinational observational post-authorisation safety study in Europe . Pharmacoepidemiol Drug Saf. 2021 Oct;30(10):1447-57. doi: 10.1002/pds.5319
Arana A , Margulis AV , Varas-Lorenzo C, Bui CL , Gilsenan A , McQuay LJ, Reynolds M , Rebordosa C , Franks B, de Vogel S, Appenteng K, Perez-Gutthann S . Validation of cardiovascular outcomes and risk factors in the Clinical Practice Research Datalink in the United Kingdom . Pharmacoepidemiol Drug Saf. 2021 Feb;30(2):237-47. doi: 10.1002/pds.5150
Gutierrez L , Bezemer ID, Dress J, Ehrenstein V, Forstner M, Franzoni C , Lassalle R, Linder M, Droz-Perroteau C, Odsbu I, Overbeek JA, Perez-Gutthann S , Pisa FE, Rascher K, Rasouliyan L, Reinold J, Rothman KJ , Saigi-Morgui N , Schaller M, Smits E, Timmer A, Toft G, von Gersdorff G, Fortuny J . Challenges in conducting a multinational European study of severe hypersensitivity reactions among recipients of intravenous iron . Poster presented at the 35th ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 27, 2019. Philadelphia, PA. [abstract] Pharmacoepidemiol Drug Saf. 2019 Aug 20; 28(S2):640. doi: 10.1002/pds.4864
Saigi N , Rebordosa C , Bui C , Aguado J , Plana E , Nuevo J, Daoud SZ, Lei A, Perez-Gutthann S , Rivero-Ferrer E . A validation exercise: identifying hospitalizations for heart failure among patients with COPD in the CPRD . Poster presented at the 35th ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 26, 2019. Philadelphia, PA. [abstract] Pharmacoepidemiol Drug Saf. 2019 Aug 20; 28(S2):334. doi: 10.1002/pds.4864
Forns J , Pottegard A, Reinders T, Poblador-Plou B, Morros R, Brandt L, Cainzos-Achirica M, Hellfritzsch M, Schink T, Prados-Torres A, Giner-Soriano M, Hallas J, Cortes J, Hagg D, Jacquot E, Deltour N, Perez-Gutthann S , Pladevall M , Reutfors J. Antidepressant use in Denmark, Germany, Spain, and Sweden from 2009 to 2014: incidence and comorbidities of antidepressant initiators . Poster presented at the 35th ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 27, 2019. Philadelphia, PA. [abstract] Pharmacoepidemiol Drug Saf. 2019 Aug 20; 28(S2):560. doi: 10.1002/pds.4864
Forns J , Cainzos-Achirica M, Hellfritzsch M, Morros R, Poblador-Plou B, Hallas J, Giner-Soriano M, Prados-Torres A, Pottegard A, Cortes J, Castellsague J, Jacquot E, Deltour N, Perez-Gutthann S , Pladevall M . Validity of ICD-9 and ICD-10 codes used to identify acute liver injury: a study in three European data sources . Pharmacoepidemiol Drug Saf. 2019 Jul;28(7):965-75. doi: 10.1002/pds.4803
Castellsague J, Poblador-Plou B, Giner-Soriano M, Linder M, Scholle O, Calingaert B , Bui C , Arana A , Laguna C, Gonzalez-Rubio F, Roso-Llorach A, Prados-Torres A, Perez-Gutthann S . Effectiveness of risk minimization measures for the use of cilostazol in United Kingdom, Spain, Sweden, and Germany . Pharmacoepidemiol Drug Saf. 2018 Sep;27(9):953-61. doi: 10.1002/pds.4584
Forns J , Cainzos-Achirica M, Hellfritzsch M, Giner-Soriano M, Poblador-Plou B, Hallas J, Morros R, Prados-Torres A, Pottegard A, Cortes J, Aguado J , Castellsague J, Jacquot E, Deltour N, Perez-Gutthann S , Pladevall M . How valid are the codes used to identify acute liver injury (ALI)? A study in 3 European data sources . Presented at the 34th ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 26, 2018. Prague, Czech Republic. [abstract] Pharmacoepidemiol Drug Saf. 2018 Aug 17; 27(S2):371-2. doi: 10.1002/pds.4629
Tormos A , Rebordosa C , Thomas S, Plana E , Rasouliyan L, Pladevall-Vila M , Fazeli-Farsani S, Deruaz-Luyet A, Brodovicz KG, Perez-Gutthann S . Time between laboratory tests and acute liver and kidney injury diagnosis codes in CPRD: are we doing it right? Poster presented at the 34th ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 26, 2018. Prague, Czech Republic. [abstract] Pharmacoepidemiol Drug Saf. 2018 Aug; 27(S2):452. doi: 10.1002/pds.4629
Cainzos-Achirica M, Varas-Lorenzo C, Pottegard A, Asmar J, Plana E , Rasmussen L, Bizouard G, Forns J , Hellfritzsch M, Zint K, Perez-Gutthann S , Pladevall-Vila M . Methodological challenges when evaluating potential off-label prescribing of drugs using electronic health care databases: a case study of dabigatran etexilate in Europe . Pharmacoepidemiol Drug Saf. 2018 Jul;27(7):713-23. doi: 10.1002/pds.4416
Setoguchi S, Kayo-Yang YH, Strom B, Stang P, Horton D, Gerhard T, Perez-Gutthann S , Leufkens B, Pinheiro S. It takes a village: raising a global community of pharmacoepidemiologists through high-quality education . Presented at the 33rd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2017. Montreal, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2017 Aug; 26(Suppl 2):5. doi: 10.1002/pds
Pladevall M , Hallas J, Schink T, Morros R, Poblador-Plou B, Forns J , Hellfritzsch M, Reinders T, Giner-Soriano M, Prados-Torres A, Cainzos-Achirica M, Pottegard A, Kollhorst B, Cortes J, Aguado J , Perlemuter G, Castellsague J, Jacquot E, Deltour N, Perez-Gutthann S . Agomelatine and risk of hospitalization for acute liver injury: nested case-control study in Spain, Germany, and Denmark . Poster presented at the 33rd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 29, 2017. Montreal, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2017 Aug; 26(Suppl 2):389. doi: 10.1002/pds
Castellsague J, Calingaert B , Poblador-Plou B, Giner-Soriano M, Linder M, Scholle O, Arana A , Bui C , Laguna C, Prados-Torres A, Roso-Llorach A, Perez-Gutthann S . Impact of risk minimization measures on the use of cilostazol in Europe . Poster presented at the 33rd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 29, 2017. Montreal, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2017 Aug; 26(Suppl 2):428. doi: 10.1002/pds
Rebordosa C , Castellsague J, Kristiansen N, Pottegard A, Plana E , Aguado J , Garcia-Gil E, Hallas J, Perez-Gutthann S . Severity of COPD in new users of aclidinium bromide and other COPD medications: a population-based study in the United Kingdom and Denmark . Presented at the 33rd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2017. Montreal, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2017 Aug; 26(Suppl 2):45-6. doi: 10.1002/pds
Cainzos-Achirica M, Varas-Lorenzo C, Pottegard A, Asmar J, Plana E , Rasmussen L, Bizouard G, Forns J , Hellfritzsch M, Zint K, Perez-Gutthann S , Pladevall-Vila M . Evaluation of potential off-label prescribing of dabigatran etexilate in France, Denmark, and the United Kingdom and associated methodological challenges . Poster presented at the 33rd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 30, 2017. Montreal, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2017 Aug; 26(Suppl 2):566. doi: 10.1002/pds
Castellsague J, Perez-Gutthann S , Calingaert B , Bui C , Varas-Lorenzo C, Arana A , Prados-Torres A, Poblador-Plou B, Gonzalez-Rubio F, Giner-Soriano M, Roso-Llorach A, Linder M, Citarella A, Scholle O, Blenk T, Garbe E. Characterization of new users of cilostazol in the UK, Spain, Sweden, and Germany . Pharmacoepidemiol Drug Saf. 2017 Jun;26(6):615-24. doi: 10.1002/pds.4167
Arana A , Varas-Lorenzo C, McQuay LJ, Ziemiecki R , Bui CL , Gilsenan AW , Rothman KJ , Atsma WJ, Appenteng K, Franks B, de Vogel S, D'Silva M, Margulis AV , Perez Gutthann S . Do individual antimuscarinic drugs to treat overactive bladder have different cardiovascular risks? A UK CPRD cohort study . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):534-5.
Castellsague J, Calingaert B , Rothman KJ , Gutierrez L , van Herk-Sukel MPP, Kuiper JG, Pottegard A, Hallas J, Berglind IA, Sundstrom A, Dedman D, Gallagher A, Kaye JA, Pardo C, Perez-Gutthann S . Probabilistic bias analysis for unmeasured confounders in a study of users of topical tacrolimus, pimecrolimus, and corticosteroids (JOELLE) study . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 26, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):142-3.
Castellsague J, Kuiper JJG, Pottegard A, Berglind IA, Dedman D, Gutierrez L , Calingaert B , van Herk-Sukel MPP, Hallas J, Sundstrom A, Gallagher A, Kaye JA, Pardo C, Rothman KJ , Perez-Gutthann S . Risk of lymphoma in users of topical tacrolimus, pimecrolimus and corticosteroids (JOELLE study) . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):494-5.
Castellsague J, van Herk-Sukel MPP, Hallas J, Sundstrom A, Gallagher A, Gutierrez L , Calingaert B , Kuiper JG, Pottegard A, Berglind IA, Dedman D, Kaye JA, Pardo C, Rothman KJ , Perez-Gutthann S . Risk of skin cancer in users of topical tacrolimus, pimecrolimus, and corticosteroids. JOint European Longitudinal Lymphoma and skin cancer Evaluation (JOELLE) study . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):527.
Castellsague J, Calingaert B , Poblador-Plou B, Giner-Soriano M, Linder M, Scholle O, Varas-Lorenzo C, Arana A , Bui C , Prados-Torres A, Gonzalez-Rubio F, Roso-Llorach A, Citarella A, Garbe E, Blenk T, Perez-Gutthann S . Characterization of new users of cilostazol in the United Kingdom, Spain, Sweden, and Germany . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 26, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):203-4.
Margulis A , Houben E, Olesen M, Hallas J, Overbeek J, Pottegard A, Ye W, Villegas D, Perez-Gutthann S , Arana A . Drug utilization study: evaluation of the use of nepafenac in the Netherlands and Denmark . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 26, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):225.
Margulis AV , Varas-Lorenzo C, Bui CL , McQuay LJ, Ziemiecki R , Reynolds M , Rebordosa C , Pladevall-Vila M , Fortuny J , Rivero-Ferrer E , Plana E , Atsma WJ, Appenteng K, Franks B, de Vogel S, D'Silva M, Perez-Gutthann S , Arana A . Validation of cardiovascular events and covariates in CPRD GOLD using questionnaires to general practitioners (GPS) . Presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 27, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):255-6.
Margulis AV , Linder M, Arana A , Pottegard A, Anveden-Berglind I, Bui CL , Kristiansen NS, Bahmanya S, McQuay LJ, Atsma WJ, Appenteng K, Franks B, de Vogel S, D'Silva M, Perez-Gutthann S , Hallas J. Patterns of use of antimuscarinic drugs to treat overactive bladder in Denmark, Sweden, and the United Kingdom . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):653.
Hallas J, Margulis AV , Pottegard A, Kristiansen N, Bui CL , Krueger W, Atsma WJ, Appenteng K, Franks B, de Vogel S, D 'Silva M, Perez-Gutthann S , Arana A . Incidence of cardiovascular events in new users of overactive bladder medications in Denmark . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):491.
Hallas J, Margulis AV , Pottegard A, Kaye JA, Kristiansen N, Bui CL , Atsma WJ, Appenteng K, Franks B, de Vogel S, D'Silva M, Perez-Gutthann S , Arana A . Elevated bladder and prostate cancer rates following initiation of OAB medication: findings from the Danish Registries . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):533.
Fortuny J , Kaye JA, Bui CL , Gilsenan AW , Bartsch J , Plana E , McQuay LJ, Calingaert B , Atsma WJ, Appenteng K, Franks B, de Vogel S, D'Silva M, Perez Gutthan S , Arana A , Margulis AV . Evaluation of free-text comments to validate common cancer diagnoses in the UK CPRD . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 26, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):58.
Linder M, Margulis AV , Anveden-Berglind I, Bahmanyar S, Bui CL , Atsma WJ, Appenteng K, Franks B, de Vogel S, D'Silva M, Perez-Gutthann S , Arana A . Cardiovascular risk in users of antimuscarinic drugs for overactive bladder: a cohort study in the Swedish National Registers . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):491-2.
Linder M, Margulis AV , Anveden-Berglind I, Bahmanyar S, Bui CL , Atsma WJ, Appenteng K, Franks B, de Vogel S, D'Silva M, Perez-Gutthann S , Arana A . Cancer risk in users of antimuscarinic drugs for overactive bladder: a cohort study in the Swedish National Registers . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):533-4.
Kuiper JG, van Herk-Sukel MPP, Castellsague J, Potttegard A, Berglind IA, Dedman D, Calingaert B , Hallas J, Sundstrom A, Gallagher AM, Kaye JA, Pardo C, Rothman KJ , Perez-Gutthann S . Utilization of tacrolimus and pimecrolimus in Europe: results from the JOint European Longitudinal Lymphoma and skin cancer Evaluation (JOELLE) study . Poster presented at the 32nd ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 28, 2016. Dublin, Ireland. [abstract] Pharmacoepidemiol Drug Saf. 2016 Aug; 25(Suppl 3):630-1.
Masclee GMC, Valkoff VE, Straatman H, Herings R, Garbe E, Schink T, Kollhorst B, Arfe A, Lucchi S, Villa M, Castellsague J, Perez-Gutthann S , Varas-Lorenzo C, Schade R, Schuemie M, Vergouwe Y, Steyerberg E, Sturkenboom M, Romio S. Individualized NSAID prescribing based on gastrointestinal and cardiovascular risks: a decision model in the SOS project . Poster presented at the 31st ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 2015. Boston, MA. [abstract] Pharmacoepidemiol Drug Saf. 2015 Sep; 24(S1):36-7. doi: 10.1002/pds.3838