var query = db.Preenrolments
                    .Where(p => (id == null || p.Id == id) &&
                        (dateFrom == null || p.DateOfBirth >= dateFrom) &&
                        (dateTo == null || p.DateOfBirth <= dateTo) &&
                        (crmState == null || p.CrmState == crmState));

                if (broker != null)
                {
                    query = query.Where(p => p.Broker.Name.Contains(broker));
                }

                var totalItemCount = query.Count();
                var subset = query
                    .Select(p => p.Build(p.Broker))
                    .Skip((page - 1)*pageSize)
                    .Take(pageSize);