$re = '/\d+=(?:(\[(?:[^][]++|(?1))*])|[^,]*)/';
$str = '34=No,46=fgbfb,48=NA,29=NA,45=dsd,49=InConclusive,43=1BHK,35=NA,38=12,39=2,27=q1,41=Others,52=fgfdg,47=fgfg,31=Chawl,33=UpperMiddleClass,37=SelfOwned,30=fdgfdgb,50=fgfdgb,51=fgfdg,32=NA,44=[[Refrigerator],Airconditioner]';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php