Analysis of the perceived difficulties that arise during the process of integrating the management systems in Implementing a management system based on international standards is a widespread practice among organizations seeking to ascertain the demands of various stakeholders. Research on the successful implementation of management systems is extensive in terms of quality management (ISO9001) (Lafuente, Bayo-Moriones & García-Cestona, 2010; Georgiev & Georgiev, 2015), environmental management (ISO 14001) (Gavronski, Paiva, Teixeira & De Andrade , 2013; Ciravegna & Da Fonseca, 2015), and occupational health and safety management (OHSAS 18001) (Granerud & Rocha, 2011; Abad, Lafuente & Vilajosana, 2013). Over the last decades, integration of management systems has become an increasingly important strategy adopted by organizations, as it is an alternative to operating with several management systems in parallel covering different technical functions (Abad, Dalmau & Vilajosana, 2014). Previous studies dealing with integrated management systems (IMS) mainly focused on three main issues, namely the structure and model of the new management system (Wilkinson & Dale, 2001; Ferguson, García & Bornay, 2002; Beckmerhagen, Berg, Karapetrovic & Willborn, 2003; Karapetrovic , 2003; Mackau, 2003; Pho & Tambo, 2014); methodologies, approaches and strategies for integration processes (Karapetrovic, 2002; Jørgensen, Remmen & Mellado, 2006; Bernardo, Casadesus, Karapetrovic & Heras, 2009; Asif, Fisscher & De Bruijn, 2010; De Oliveira, 2013); and benefits following the integration of different management systems (Douglas & Glen, 2000; Khanna, Laroiya & Sharma, 2010; Zeng, Xie, Tam & Shen, 2011; Tarí, Molina-Azorín & Heras, 2012; Abad et al., 2014 ; Bernardo, Simon, Tari & Molina-Azorin, 2015). However, IMS also faces distinct problems that can undermine the integration process and its results (Bernardo, Casadesus, Karapetrovic & Heras, 2012a). To avoid management system integration failures, organizations should also turn their attention to the difficulties associated with implementing and maintaining a new IMS (López-Fresno, 2010). However, the IMS literature has not addressed in depth the difficulties associated with management system integration. Early studies analyzed IMS from a theoretical perspective, and most identified difficulties associated with the integration process (Tranmer, 1996; Jonker & Klaver, 1998; Wilkinson & Dale, 1999; Karapetrovic & Willborn, 1998). Recently, research has begun to pay attention to and document the difficulties resulting from the implementation of IMS (Heras, Bernardo & Casadesús, 2007; Zeng, Shi & Lou, 2007; Salomone, 2008; Zeng, Tam & Tam, 2008; Simon, Karapetrovic & Casadesus, 2012). Despite the increased interest in understanding how these adversities arise and affect the resulting STIs (Bernardo et al., 2012a), there is still a dearth of empirical research on this critical aspect of STIs. In line with this argument, the main objective guiding this paper is to empirically examine the difficulties that arise in the management systems integration process and to analyze the circumstances that trigger these difficulties. The remainder of this paper is organized as follows. Section two presents the theoretical framework. Section three describes the selected data and methodology. The empirical results are offered in section four, and the final conclusions are presented in section five.
