Table 2.

PPC: classification of articles by design or main focus (N = 27)

Kind of study	N	Reference
Comments/reflections	13	Calhoun 1997 [12], Hoeldtke 2001 [13], Milstein 2005 [14], Bhatia 2006 [15], Buus-Frank 2006 [16], Pearce 2006 [17], Sumner 2006 [18], Munson 2007 [19], Pignotti 2007 [20], Roy 2007 [21], Williams 2008 [22], Bétrémieux 2009 [23], Payot 2009 [24]
Clinical studies	8
Case reports	3	Watkins 1989 [25], Flower 1992 [26], Nuutila 2008 [27]
Quantitative (series)	4	Calhoun 2003 [1], D'Almeida 2006 [28], Breeze 2007 [29], Leuthner 2007 [30]
Qualitative (series)	1	Chitty 1996 [31]
Guidelines/clinical practice proposals	5	Craig 2003 [32], Leuthner 2004 [33], Leuthner 2004 (b) [34], Ramer-Chrastek 2005 [35], Howard 2006 [36]
Designing/describing a PC programme	1	Catlin 2002 [37]