(a)

Author (year)	Prevalence	Definition
Perris (1966) [12]	4.5% among all BD patients	M ≥ 1, D = 0
Abrams and Taylor (1974) [13]	28% of BD I patients	M-number not defined, D = 0
Nurnberger et al. (1979) [18]	15.7% of BD I patients	M ≥ 1 hospitalization, D = no hospitalization or somatic treatment
Abrams et al. (1979) [14]	18% of BD patients	M ≥ 2, D = 0
Perris (1982) [10]	1.1% of BD patients	M ≥ 1, D = 0
Pfohl et al. (1982) [15]	35.2% of hospitalized BD patients	M ≥ 1, D = 0
Rao et al. (1982) [16]	2.7% of lithium clinic patients	Only M during follow-up, D = 0
Venkoba Rao and Madhavan (1983) [17]	12% of BD patients (age of onset >60 years)	Only M during follow-up, D = 0
Srinivasan et al. (1982) [19]	40% of hospitalized BD patients	M ≥ 3, D = 0
Margoob and Dutta (1988) [40]	42% of all BD patients	M = not defined, D = not defined
Khanna et al. (1992) [20]	44% of hospitalized BD patients	M ≥ 4, D = 0
Avasthi et al. (1996) [21]	6.45% of all affective disorders	M ≥ 3, D = 0
Aghanwa (2001) [22]	47.2% of all BD patients	M ≥ 3 (includes hypomania as well) and affective illness for at least 4 years, D = 0
Yazici et al. (2002) [23]	16.3% of BD I patients	M ≥ 4 and at least 4 years of follow-up, D = 0
Perugi et al. (2007) [25]	21.8% of hospitalized BD I patients	M ≥ 3 and affective illness of at least 10 years, D = 0

D: depressive episode; M: manic episode.