function appointments_update_appointment_status($app_id, $new_status)
{
    global $wpdb;
    $app = appointments_get_appointment($app_id);
    if (!$app) {
        return false;
    }
    $old_status = $app->status;
    if ($old_status === $new_status) {
        return false;
    }
    $allowed_status = appointments_get_statuses();
    if (!array_key_exists($new_status, $allowed_status)) {
        return false;
    }
    $table = appointments_get_table('appointments');
    $result = $wpdb->update($table, array('status' => $new_status), array('ID' => $app_id), array('%s'), array('%d'));
    if ($result) {
        if ('removed' == $new_status) {
            do_action('app_removed', $app_id);
        }
        appointments_clear_appointment_cache($app_id);
        if ('removed' === $new_status) {
            appointments_send_removal_notification($app_id);
        }
        do_action('wpmudev_appointments_update_appointment_status', $app_id, $new_status, $old_status);
        return true;
    }
    return false;
}
<div class="tablenav top">

	<div class="alignleft actions">
		<form id="app-bulk-change-form" method="post" action="<?php 
echo add_query_arg('page', 'appointments');
?>
" >
			<input type="hidden" value="appointments" name="page" />
			<input type="hidden" value="1" name="app_status_change" />
			<select name="app_new_status" style='float:none;'>
				<option value=""><?php 
_e('Bulk status change', 'appointments');
?>
</option>
				<?php 
foreach (appointments_get_statuses() as $value => $name) {
    echo '<option value="' . esc_attr($value) . '" class="hide-if-no-js">' . $name . '</option>';
}
?>
			</select>
			<input type="submit" class="button app-change-status-btn" value="<?php 
_e('Change Status', 'appointments');
?>
" />
		</form>
	</div>
	<script type="text/javascript">
	jQuery(document).ready(function($){
		$(".app-change-status-btn").click(function(e){
			var button = $(this);
			e.preventDefault();