[Tex/LaTex] Itemize inside longtable

Question

I have the following (Non-working) example.

\renewcommand*{\arraystretch}{1.8}
\begin{longtable}{lcl}
    \caption{Summary of proven determinants for falling}\\ \toprule
    \label{tab:FallPredictionVariables}
    \textbf{Author} &\textbf{Subject count (M:F)} & \textbf{Determinants}\\
    \midrule

    \noindent Author 1 &
    1780 (?) & 
    \begin{itemize}%[label={--},noitemsep,leftmargin=*,topsep=0pt,partopsep=0pt]
        \item Recent falls (last 2 months)
        \item Agitation
        \item Frequent toileting
        \item Visual impairment
    \end{itemize}\\

    \noindent Author 2 &
    311 (?) &
    \begin{itemize}%[label={--},noitemsep,leftmargin=*,topsep=0pt,partopsep=0pt]
        \item Posture sway
        \item Two or more falls in previous year
        \item Low hand grip strength
        \item Depressive state of mind
    \end{itemize}\\
        \bottomrule

\end{longtable}

However, it works OK outside a longtable environment:

\renewcommand*{\arraystretch}{1.8}
\begin{table}
\centering
    \caption{Summary of proven determinants for falling} 
    \label{tab:FallPredictionVariables}
    \begin{tabular}{lcp{60mm}}
    \toprule
    \textbf{Author} &\textbf{Subject count (M:F)} & \textbf{Determinants}\\
    \midrule

    \noindent Author 1 &
    1780 (?) & 
    \begin{itemize}[label={--},noitemsep,leftmargin=*,topsep=0pt,partopsep=0pt]
        \item Recent falls (last 2 months)
        \item Agitation
        \item Frequent toileting
        \item Visual impairment
    \end{itemize}\\

    \noindent Author 2 &
    311 (?) &
    \begin{itemize}[label={--},noitemsep,leftmargin=*,topsep=0pt,partopsep=0pt]
        \item Posture sway
        \item Two or more falls in previous year
        \item Low hand grip strength
        \item Depressive state of mind
    \end{itemize}\\
        \bottomrule

        \end{tabular}

\end{table}

As you can see in the picture below, it does what I'm expecting (except there is some vertical space over the first item that I would like to remove, and the solutions posted in How to reduce vertical space itemize environment inside table only seem to work for tabularx environments).

I'm unable to make my code work inside longtable, and I really need it (the complete table is very long).

Any ideas for both things:

1. To be able to have itemize inside longtable environment
2. Eliminate the extra space for the first item

PS: This is the preamble for both examples:

\documentclass[a4paper,twoside,11pt,openright]{report}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{longtable}  
\usepackage[inline]{enumitem}   
\usepackage{booktabs}

\begin{document}
...
\end{document}

Answer 1

Without a full MWE, I've taken some code from Przemysław Scherwentke's answer:

\documentclass{report}
\usepackage{longtable}% http://ctan.org/pkg/longtable
\usepackage{array,booktabs,enumitem}% http://ctan.org/pkg/{array,booktabs,enumitem}
\newcolumntype{P}[1]{>{\endgraf\vspace*{-\baselineskip}}p{#1}}

\begin{document}

\renewcommand*{\arraystretch}{1.8}
\begin{longtable}{p{4cm}p{4cm}P{6cm}}
  \caption{Summary of proven determinants for falling}\label{tab:FallPredictionVariables} \\
  \toprule
  \textbf{Author} &\textbf{Subject count (M:F)} & \multicolumn{1}{l}{\textbf{Determinants}} \\
  \midrule

  \noindent Author 1 &
  1780 (?) & 
  \begin{itemize}[label={--},noitemsep,leftmargin=*,topsep=0pt,partopsep=0pt]
    \item Recent falls (last 2 months)
    \item Agitation
    \item Frequent toileting
    \item Visual impairment
  \end{itemize}\\

  \noindent Author 2 &
  311 (?) & 
  \begin{itemize}[label={--},noitemsep,leftmargin=*,topsep=0pt,partopsep=0pt]
    \item Posture sway
    \item Two or more falls in previous year
    \item Low hand grip strength
    \item Depressive state of mind
  \end{itemize}\\
  \bottomrule
\end{longtable}

\end{document}

The P{<len>} column type (thanks to array) inserts a "vertical unskip" so that the first item aligns properly with the remainder of the table.

The assumption is that the last P-column only contains lists, of course. If not, a separate \multicolumn has to be issued like with the heading Determinants.