Increased Risk of CTS (Moderate Evidence)
Moderate evidence supports that the following factors are associated with the increased risk of developing carpal tunnel syndrome (CTS):
• Peri-menopausal
• Wrist Ratio/Index
• Rheumatoid Arthritis
• Psychosocial factors
• Distal upper extremity tendinopathies
• Gardening
• ACGIH Hand Activity Level at or above threshold
• Assembly line work
• Computer work
• Vibration
• Tendonitis
• Workplace forceful grip/exertion

Rationale
Peri-menopausal status was shown in one high quality study (Hakim, 2002) to be associated with an increased risk of CTS development, but no association was found between CTS and post-menopausal status.
 
Wrist ratio/index (ratio of wrist depth to width >0.7mm) was significantly associated with an increased risk of CTS in one high (Armstrong, 2008) and six moderate quality studies (Boz, 2004; Gordon, 1988; Hlebs, 2014; Moghtaderi, 2005; Sabry, 2009; Shariff-Mollayousefi, 2008). 
 
Rheumatoid arthritis was associated with an increased risk of CTS in one high quality (Garg, 2012) and one moderate quality study (Burt, 2011).  One moderate quality study (Geoghegan, 2004) showed an association between osteoarthritis and CTS.
 
Mood (“felt down, blue or depressed always/never, compared to seldom”) was associated with increased risk of CTS in one high quality study (Garg, 2012). One moderate quality study (Coggon, 2013) showed an association with increased risk based on self-rated mental health.
 
Hand, wrist or elbow tendinopathies (musculoskeletal conditions) were associated with increased risk of CTS in one high quality (Garg, 2012) and two moderate quality studies (Aktas, 2008; Nordstrom, 1997).
 
Gardening was associated with an increased risk of developing CTS in one high quality study (Garg, 2012).
 
The American Conference of Governmental Industrial Hygienists (ACGIH) hand activity level (HAL) is a standardized method for evaluating jobs that involves expert observation, direct measurement or video analysis to assess both pinch/grip force and hand/wrist repetition rate. There was one high quality (Bonfiglioli, 2013) and three moderate quality (Burt, 2011; Burt, 2013; Violante, 2007) studies, showing significant associations to increased risk of CTS when the ACGIH HAL was at or above the threshold limit.  In addition, there was one high quality study (Garg, 2012) that showed an association with CTS by hazard ratio but this finding was limited by a wide confidence interval that included a value of 1.0 (HR: 2.01, CI: 0.8-5.0).
 
Assembly line work was associated with increased risk for the development of CTS in one high quality (Armstrong, 2008) and two low quality studies (Bonfiglioli, 2006; Lecler, 1998).
 
Computer work was significantly associated with increased risk of CTS by three moderate quality studies (Ali, 2006; Coggon, 2013; Eletheriou, 2012).  One study found an increased association with an average of greater than eight hours of computer use per day and more than four years of computer work (Ali, 2006).  Another study found an association between an increased risk of CTS and working on a keyboard or mouse for more than four hours per day (Coggon, 2013).  The third study found an association with a very high number of keystrokes typed per year and a higher risk of CTS (Eleftheriou, 2012). There was one moderate quality study (Ali, 2006) evaluating internet use for leisure, which also found a significant result for increasing risk of CTS.
 
The use of vibrating hand-held tools was associated with an increased risk of CTS in one high quality (Armstrong, 2008) and three moderate quality studies (Coggon, 2013; Dale, 2014; Nordstrom, 1997).
 
Tendonitis in the shoulder, hand, finger, or wrist was shown to increase risk of CTS by one high quality (Armstrong, 2008) and one low quality study (Werner, 2005).
 
Workplace forceful grip/exertion was found to be significantly associated with increased risk of CTS by one high quality (Armstrong, 2008) and four moderate quality studies (Burt, 2011; Burt, 2013; Dale, 2014; Evanoff, 2012).